Sepolia Testnet

Contract

0x8b729A33f86597D134F0382dA22D47939D2c88B2
Transaction Hash
Method
Block
From
To
Set Whitelist NF...72405012024-12-09 1:50:126 hrs ago1733709012IN
0x8b729A33...39D2c88B2
0 ETH0.000020940.45005749
Set Whitelist NF...72211632024-12-06 5:30:123 days ago1733463012IN
0x8b729A33...39D2c88B2
0 ETH0.000085631.83960562
Set Whitelist NF...72013332024-12-03 7:10:126 days ago1733209812IN
0x8b729A33...39D2c88B2
0 ETH0.0006388913.72485032
Set Whitelist NF...71484682024-11-25 8:15:1214 days ago1732522512IN
0x8b729A33...39D2c88B2
0 ETH0.000415098.91727084
Buy NFTETH71217252024-11-21 9:29:3617 days ago1732181376IN
0x8b729A33...39D2c88B2
0.037 ETH0.0061508749.76197568
Set Whitelist NF...71216072024-11-21 9:05:1217 days ago1732179912IN
0x8b729A33...39D2c88B2
0 ETH0.0017471137.53210551
Set Whitelist NF...70661712024-11-13 4:30:2426 days ago1731472224IN
0x8b729A33...39D2c88B2
0 ETH0.00001020.21922542
Set Whitelist NF...69892062024-11-01 9:15:1237 days ago1730452512IN
0x8b729A33...39D2c88B2
0 ETH0.0006190413.29840893
Accept Offer NFT69600892024-10-28 2:09:4842 days ago1730081388IN
0x8b729A33...39D2c88B2
0 ETH0.000336672.38346404
Auction NFT69600222024-10-28 1:55:1242 days ago1730080512IN
0x8b729A33...39D2c88B2
0 ETH0.000101010.96180402
Buy NFT Normal69599822024-10-28 1:46:4842 days ago1730080008IN
0x8b729A33...39D2c88B2
0 ETH0.000356252.24100139
Buy NFT Normal69420232024-10-25 10:13:3644 days ago1729851216IN
0x8b729A33...39D2c88B2
0 ETH0.00058424.54915983
Buy NFTETH68536692024-10-11 2:06:4859 days ago1728612408IN
0x8b729A33...39D2c88B2
0.003 ETH0.000186421.50806964
Buy NFTETH68492792024-10-10 8:32:4859 days ago1728549168IN
0x8b729A33...39D2c88B2
0.001 ETH0.000175341.50140786
Buy NFT Normal68492282024-10-10 8:20:2459 days ago1728548424IN
0x8b729A33...39D2c88B2
0 ETH0.000221861.50015348
Auction NFT68485342024-10-10 5:35:2460 days ago1728538524IN
0x8b729A33...39D2c88B2
0 ETH0.000000140.00150006
Auction NFT68483432024-10-10 4:50:1260 days ago1728535812IN
0x8b729A33...39D2c88B2
0 ETH0.000000160.00150004
Buy NFTETH68431192024-10-09 8:07:0061 days ago1728461220IN
0x8b729A33...39D2c88B2
0.001 ETH0.000176251.50884616
Auction NFT68430692024-10-09 7:55:1261 days ago1728460512IN
0x8b729A33...39D2c88B2
0 ETH0.000000320.00286236
Accept Offer NFT68369112024-10-08 7:31:4862 days ago1728372708IN
0x8b729A33...39D2c88B2
0 ETH0.00039222.5787098
Auction NFT68369042024-10-08 7:30:1262 days ago1728372612IN
0x8b729A33...39D2c88B2
0 ETH0.000235611.8266026
Buy NFT Normal68368812024-10-08 7:24:1262 days ago1728372252IN
0x8b729A33...39D2c88B2
0 ETH0.000389412.80007033
Buy NFTETH68368332024-10-08 7:11:3662 days ago1728371496IN
0x8b729A33...39D2c88B2
0.003 ETH0.000303842.66731939
Buy NFT Normal68313512024-10-07 9:23:4862 days ago1728293028IN
0x8b729A33...39D2c88B2
0 ETH0.01995432161.94716575
Set Whitelist NF...67871482024-09-30 10:10:1269 days ago1727691012IN
0x8b729A33...39D2c88B2
0 ETH0.01271672273.18410685
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Latest 25 internal transactions (View All)

Advanced mode:
Parent Transaction Hash Block From To
71217252024-11-21 9:29:3617 days ago1732181376
0x8b729A33...39D2c88B2
0.03293 ETH
71217252024-11-21 9:29:3617 days ago1732181376
0x8b729A33...39D2c88B2
0.00407 ETH
68536692024-10-11 2:06:4859 days ago1728612408
0x8b729A33...39D2c88B2
0.0027 ETH
68536692024-10-11 2:06:4859 days ago1728612408
0x8b729A33...39D2c88B2
0.0003 ETH
68492792024-10-10 8:32:4859 days ago1728549168
0x8b729A33...39D2c88B2
0.0007 ETH
68492792024-10-10 8:32:4859 days ago1728549168
0x8b729A33...39D2c88B2
0.0001 ETH
68492792024-10-10 8:32:4859 days ago1728549168
0x8b729A33...39D2c88B2
0.0002 ETH
68431192024-10-09 8:07:0061 days ago1728461220
0x8b729A33...39D2c88B2
0.0007 ETH
68431192024-10-09 8:07:0061 days ago1728461220
0x8b729A33...39D2c88B2
0.0001 ETH
68431192024-10-09 8:07:0061 days ago1728461220
0x8b729A33...39D2c88B2
0.0002 ETH
68368332024-10-08 7:11:3662 days ago1728371496
0x8b729A33...39D2c88B2
0.003 ETH
67437562024-09-23 7:06:0077 days ago1727075160
0x8b729A33...39D2c88B2
0.00044 ETH
67437562024-09-23 7:06:0077 days ago1727075160
0x8b729A33...39D2c88B2
0.00044 ETH
67437562024-09-23 7:06:0077 days ago1727075160
0x8b729A33...39D2c88B2
0.04312 ETH
67139072024-09-18 7:20:2482 days ago1726644024
0x8b729A33...39D2c88B2
0.00151 ETH
67139072024-09-18 7:20:2482 days ago1726644024
0x8b729A33...39D2c88B2
0.00151 ETH
67139072024-09-18 7:20:2482 days ago1726644024
0x8b729A33...39D2c88B2
0.14798 ETH
67138132024-09-18 6:59:0082 days ago1726642740
0x8b729A33...39D2c88B2
0.00304 ETH
67138132024-09-18 6:59:0082 days ago1726642740
0x8b729A33...39D2c88B2
0.00304 ETH
67138132024-09-18 6:59:0082 days ago1726642740
0x8b729A33...39D2c88B2
0.29792 ETH
67016102024-09-16 8:12:1284 days ago1726474332
0x8b729A33...39D2c88B2
0.00045 ETH
67016102024-09-16 8:12:1284 days ago1726474332
0x8b729A33...39D2c88B2
0.00045 ETH
67016102024-09-16 8:12:1284 days ago1726474332
0x8b729A33...39D2c88B2
0.0441 ETH
67006012024-09-16 4:23:3684 days ago1726460616
0x8b729A33...39D2c88B2
0.00056 ETH
67006012024-09-16 4:23:3684 days ago1726460616
0x8b729A33...39D2c88B2
0.00056 ETH
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Similar Match Source Code
This contract matches the deployed Bytecode of the Source Code for Contract 0x40293385...0b4f21B1E
The constructor portion of the code might be different and could alter the actual behaviour of the contract

Contract Name:
ExchangeNFTCreator

Compiler Version
v0.8.4+commit.c7e474f2

Optimization Enabled:
Yes with 200 runs

Other Settings:
default evmVersion

Contract Source Code (Solidity Standard Json-Input format)

File 1 of 17 : ExchangeNFTCreator.sol
//SPDX-License-Identifier: MIT

import "./libraries/SafeMath.sol";
import "./libraries/Address.sol";
import "./libraries/Context.sol";
import "./libraries/Ownable.sol";
import "./libraries/TransferHelper.sol";
import "./libraries/ECDSA.sol";
import "./libraries/Operator.sol";
import "./interfaces/ERC20/IERC20.sol";
import "./interfaces/ERC20/IERC20Metadata.sol";
import "./interfaces/ERC20/SafeERC20.sol";
import "./interfaces/ERC20/ERC20.sol";
import "./interfaces/IStableToken.sol";
import "./interfaces/ERC721A/IERC721A.sol";
import "./interfaces/ERC721A/ERC721A.sol";


pragma solidity ^0.8.4;


contract ExchangeNFTCreator is Ownable, Operator {
    using ECDSA for bytes32;
    using SafeERC20 for ERC20;
    using SafeMath for uint256;

    // address public ERC721;

    // Address is owner of ERC721
    // address public admin;

    // Mitigating Replay Attacks
    mapping(address => mapping(uint256 => bool)) seenNonces;

    // Addresses running auction NFT
    mapping(address => bool) public whitelistAddress;
    mapping(address => bool) public whitelistNFTAddress;

    struct Data {
        address[6] tradeAddress;
        uint256[4] attributes;
    }

    // Events
    // addrs: from, to, token
    event BuyNFTNormal(address[3] addrs, uint256 tokenId, uint256 amount);
    event BuyNFTETH(address[3] addrs, uint256 tokenId, uint256 amount);
    event AuctionNFT(address[3] addrs, uint256 tokenId, uint256 amount);
    event AcceptOfferNFT(address[3] addrs, uint256 tokenId, uint256 amount);

    constructor() public {
        whitelistAddress[msg.sender] = true;
    //    admin = msg.sender;
    }

    // function setNFTAddress(address _nft) public onlyOwner {
    //     ERC721 = _nft;
    // }

    function setWhitelistAddress(address _address, bool approved)
        public
        onlyOperator
    {
        whitelistAddress[_address] = approved;
    }

    function setWhitelistNFTAddress(address _address, bool approved)
        public
        onlyOperator
    {
        whitelistNFTAddress[_address] = approved;
    }

    // function setAdminAddress(address _admin) public onlyOperator {
    //     admin = _admin;
    // }

    modifier verifySignature(
        uint256 nonce,
        address[6] memory _tradeAddress,
        uint256[4] memory _attributes,
        bytes memory signature
    ) {
        // This recreates the message hash that was signed on the client.
        bytes32 hash = keccak256(
            abi.encodePacked(
                msg.sender,
                nonce,
                _tradeAddress,
                _attributes
            )
        );
        bytes32 messageHash = hash.toEthSignedMessageHash();
        // Verify that the message's signer is the owner of the order
        require(messageHash.recover(signature) == owner(), "Invalid signature");
        require(!seenNonces[msg.sender][nonce], "Used nonce");
        seenNonces[msg.sender][nonce] = true;
        _;
    }

    function checkFeeProductExits(
        address[6] memory _tradeAddress,
        uint256[4] memory _attributes
    ) private returns (uint256 amount, uint256 feeOwner, uint256 feeAdmin) {
        uint256 totalFeeTrade;
        // Check fee for owner
        if (_tradeAddress[3] != address(0)) {
            feeOwner = _attributes[0].mul(_attributes[2]).div(1000);
            totalFeeTrade += feeOwner;
        }
        // Check fee for admin
        if (_tradeAddress[4] != address(0)) {
            feeAdmin = _attributes[0].mul(_attributes[3]).div(1000);
            totalFeeTrade += feeAdmin;
        }

        amount = _attributes[0].sub(totalFeeTrade);
    }

    // Buy NFT normal by token ERC-20
    // address[6]: buyer, seller, token, fee, feeAdmin, NFT contract
    // uint256[4]: amount, tokenId, feePercent, feePercentAdmin
    function buyNFTNormal(
        address[6] memory _tradeAddress,
        uint256[4] memory _attributes,
        uint256 nonce,
        bytes memory signature
    ) external verifySignature(nonce, _tradeAddress, _attributes, signature) {
        Data memory tradeInfo = Data({
            tradeAddress: _tradeAddress,
            attributes: _attributes
        });

        require(
            whitelistNFTAddress[tradeInfo.tradeAddress[5]] == true,
            "NFT is not in whitelist"
        );

        // check allowance of buyer
        require(
            IERC20(tradeInfo.tradeAddress[2]).allowance(msg.sender, address(this)) >=
                tradeInfo.attributes[0],
            "token allowance too low"
        );
        (uint256 amount, uint256 feeOwner, uint256 feeAdmin) = checkFeeProductExits(
            tradeInfo.tradeAddress,
            tradeInfo.attributes
        );

        if (feeOwner != 0) {
            // transfer token to fee address
            ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
                tradeInfo.tradeAddress[0],
                tradeInfo.tradeAddress[3],
                feeOwner
            );
        }

        if (feeAdmin != 0) {
            // transfer token to fee address
            ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
                tradeInfo.tradeAddress[0],
                tradeInfo.tradeAddress[4],
                feeAdmin
            );
        }


        // transfer token from buyer to seller
        ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
            msg.sender,
            tradeInfo.tradeAddress[1],
            amount
        );
        IERC721A(tradeInfo.tradeAddress[5]).safeTransferFrom(
            tradeInfo.tradeAddress[1],
            msg.sender,
            tradeInfo.attributes[1]
        );
        emit BuyNFTNormal(
            [msg.sender, tradeInfo.tradeAddress[1], tradeInfo.tradeAddress[2]],
            tradeInfo.attributes[1],
            tradeInfo.attributes[0]
        );
    }

    // Buy NFT normal by ETH
    // address[6]: buyer, seller, token, fee, feeAdmin, NFT contract
    // uint256[4]: amount, tokenId, feePercent, feePercentAdmin
    function buyNFTETH(
        address[6] memory _tradeAddress,
        uint256[4] memory _attributes,
        uint256 nonce,
        bytes memory signature
    )
        external
        payable
        verifySignature(nonce, _tradeAddress, _attributes, signature)
    {
        Data memory tradeInfo = Data({
            tradeAddress: _tradeAddress,
            attributes: _attributes
        });

        require(
            whitelistNFTAddress[tradeInfo.tradeAddress[5]] == true,
            "NFT is not in whitelist"
        );

        (uint256 amount, uint256 feeOwner, uint256 feeAdmin) = checkFeeProductExits(
            tradeInfo.tradeAddress,
            tradeInfo.attributes
        );
        // transfer eth to fee address
        if (feeOwner != 0) {
            TransferHelper.safeTransferETH(tradeInfo.tradeAddress[3], feeOwner);
        }

        // transfer eth to admin address
        if (feeAdmin != 0) {
            TransferHelper.safeTransferETH(tradeInfo.tradeAddress[4], feeAdmin);
        }

        TransferHelper.safeTransferETH(tradeInfo.tradeAddress[1], amount);

        IERC721A(tradeInfo.tradeAddress[5]).safeTransferFrom(
            tradeInfo.tradeAddress[1],
            msg.sender,
            tradeInfo.attributes[1]
        );
        // refund dust eth, if any
        if (msg.value > tradeInfo.attributes[0])
            TransferHelper.safeTransferETH(
                msg.sender,
                msg.value - tradeInfo.attributes[0]
            );
        emit BuyNFTETH(
            [msg.sender, tradeInfo.tradeAddress[1], tradeInfo.tradeAddress[2]],
            tradeInfo.attributes[1],
            tradeInfo.attributes[0]
        );
    }

    // Auction NFT
    // address[6]: buyer, seller, token, fee, feeAdmin, NFT contract
    // uint256[4]: amount, tokenId, feePercent, feePercentAdmin
    function auctionNFT(
        address[6] memory _tradeAddress,
        uint256[4] memory _attributes
    ) external {
        Data memory tradeInfo = Data({
            tradeAddress: _tradeAddress,
            attributes: _attributes
        });
        // Check address execute auction
        require(
            whitelistAddress[msg.sender] == true,
            "Address is not in whitelist"
        );
        require(
            whitelistNFTAddress[tradeInfo.tradeAddress[5]] == true,
            "NFT is not in whitelist"
        );

        // check allowance of buyer
        require(
            IERC20(tradeInfo.tradeAddress[2]).allowance(
                tradeInfo.tradeAddress[0],
                address(this)
            ) >= tradeInfo.attributes[0],
            "token allowance too low"
        );
        if (tradeInfo.tradeAddress[1] == owner()) {
            require(
                IERC721A(tradeInfo.tradeAddress[5]).isApprovedForAll(owner(), address(this)),
                "tokenId do not approve for contract"
            );
        } else {
            require(
                IERC721A(tradeInfo.tradeAddress[5]).getApproved(tradeInfo.attributes[1]) == address(this),
                "tokenId do not approve for contract"
            );
        }

        (uint256 amount, uint256 feeOwner, uint256 feeAdmin) = checkFeeProductExits(
            tradeInfo.tradeAddress,
            tradeInfo.attributes
        );
        if (feeOwner != 0) {
            // transfer token to fee address
            ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
                tradeInfo.tradeAddress[0],
                tradeInfo.tradeAddress[3],
                feeOwner
            );
        }

        if (feeAdmin != 0) {
            // transfer token to fee address
            ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
                tradeInfo.tradeAddress[0],
                tradeInfo.tradeAddress[4],
                feeAdmin
            );
        }

        // transfer token from buyer to seller
        ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
            tradeInfo.tradeAddress[0],
            tradeInfo.tradeAddress[1],
            amount
        );
        IERC721A(tradeInfo.tradeAddress[5]).safeTransferFrom(
            tradeInfo.tradeAddress[1],
            tradeInfo.tradeAddress[0],
            tradeInfo.attributes[1]
        );
        emit AuctionNFT(
            [msg.sender, tradeInfo.tradeAddress[1], tradeInfo.tradeAddress[2]],
            tradeInfo.attributes[1],
            tradeInfo.attributes[0]
        );
    }

    // Accept offer from buyer
    // address[6]: buyer, seller, token, fee, feeAdmin, NFT contract
    // uint256[4]: amount, tokenId, feePercent, feePercentAdmin
    function acceptOfferNFT(
        address[6] memory _tradeAddress,
        uint256[4] memory _attributes,
        uint256 nonce,
        bytes memory signature
    ) external verifySignature(nonce, _tradeAddress, _attributes, signature) {
        Data memory tradeInfo = Data({
            tradeAddress: _tradeAddress,
            attributes: _attributes
        });

        require(
            whitelistNFTAddress[tradeInfo.tradeAddress[5]] == true,
            "NFT is not in whitelist"
        );

        require(
            IERC721A(tradeInfo.tradeAddress[5]).getApproved(tradeInfo.attributes[1]) == address(this),
            "tokenId do not approve for contract"
        );
        // check allowance of buyer
        require(
            IERC20(tradeInfo.tradeAddress[2]).allowance(
                tradeInfo.tradeAddress[0],
                address(this)
            ) >= tradeInfo.attributes[0],
            "token allowance too low"
        );

        (uint256 amount, uint256 feeOwner, uint256 feeAdmin) = checkFeeProductExits(
            tradeInfo.tradeAddress,
            tradeInfo.attributes
        );
        if (feeOwner != 0) {
            // transfer token to fee address
            ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
                tradeInfo.tradeAddress[0],
                tradeInfo.tradeAddress[3],
                feeOwner
            );
        }

        if (feeAdmin != 0) {
            // transfer token to fee address
            ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
                tradeInfo.tradeAddress[0],
                tradeInfo.tradeAddress[4],
                feeAdmin
            );
        }

        // transfer token from buyer to seller
        ERC20(tradeInfo.tradeAddress[2]).safeTransferFrom(
            tradeInfo.tradeAddress[0],
            msg.sender,
            amount
        );

        IERC721A(tradeInfo.tradeAddress[5]).safeTransferFrom(
            tradeInfo.tradeAddress[1],
            tradeInfo.tradeAddress[0],
            tradeInfo.attributes[1]
        );
        emit AcceptOfferNFT(
            [msg.sender, tradeInfo.tradeAddress[1], tradeInfo.tradeAddress[2]],
            tradeInfo.attributes[1],
            tradeInfo.attributes[0]
        );
    }
}

File 2 of 17 : draft-IERC20Permit.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.4;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

File 3 of 17 : ERC20.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.4;

import "./IERC20.sol";
import "./IERC20Metadata.sol";
import "../../libraries/Context.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overridden;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        _balances[to] += amount;

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

File 4 of 17 : IERC20.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.4;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}

File 5 of 17 : IERC20Metadata.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.4;

import "./IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

File 6 of 17 : SafeERC20.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.4;

import "./IERC20.sol";
import "./draft-IERC20Permit.sol";
import "../../libraries/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

File 7 of 17 : ERC721A.sol
// SPDX-License-Identifier: MIT
// ERC721A Contracts v4.2.2
pragma solidity ^0.8.4;

import "./IERC721A.sol";

/**
 * @dev Interface of ERC721 token receiver.
 */
interface ERC721A__IERC721Receiver {
  function onERC721Received(
    address operator,
    address from,
    uint256 tokenId,
    bytes calldata data
  ) external returns (bytes4);
}

/**
 * @title ERC721A
 *
 * @dev Implementation of the [ERC721](https://eips.ethereum.org/EIPS/eip-721)
 * Non-Fungible Token Standard, including the Metadata extension.
 * Optimized for lower gas during batch mints.
 *
 * Token IDs are minted in sequential order (e.g. 0, 1, 2, 3, ...)
 * starting from `_startTokenId()`.
 *
 * Assumptions:
 *
 * - An owner cannot have more than 2**64 - 1 (max value of uint64) of supply.
 * - The maximum token ID cannot exceed 2**256 - 1 (max value of uint256).
 */
contract ERC721A is IERC721A {
  // Reference type for token approval.

  struct TokenApprovalRef {
    address value;
  }

  // =============================================================
  //                           CONSTANTS
  // =============================================================

  // Mask of an entry in packed address data.
  uint256 private constant _BITMASK_ADDRESS_DATA_ENTRY = (1 << 64) - 1;

  // The bit position of `numberMinted` in packed address data.
  uint256 private constant _BITPOS_NUMBER_MINTED = 64;

  // The bit position of `numberBurned` in packed address data.
  uint256 private constant _BITPOS_NUMBER_BURNED = 128;

  // The bit position of `aux` in packed address data.
  uint256 private constant _BITPOS_AUX = 192;

  // Mask of all 256 bits in packed address data except the 64 bits for `aux`.
  uint256 private constant _BITMASK_AUX_COMPLEMENT = (1 << 192) - 1;

  // The bit position of `startTimestamp` in packed ownership.
  uint256 private constant _BITPOS_START_TIMESTAMP = 160;

  // The bit mask of the `burned` bit in packed ownership.
  uint256 private constant _BITMASK_BURNED = 1 << 224;

  // The bit position of the `nextInitialized` bit in packed ownership.
  uint256 private constant _BITPOS_NEXT_INITIALIZED = 225;

  // The bit mask of the `nextInitialized` bit in packed ownership.
  uint256 private constant _BITMASK_NEXT_INITIALIZED = 1 << 225;

  // The bit position of `extraData` in packed ownership.
  uint256 private constant _BITPOS_EXTRA_DATA = 232;

  // Mask of all 256 bits in a packed ownership except the 24 bits for `extraData`.
  uint256 private constant _BITMASK_EXTRA_DATA_COMPLEMENT = (1 << 232) - 1;

  // The mask of the lower 160 bits for addresses.
  uint256 private constant _BITMASK_ADDRESS = (1 << 160) - 1;

  // The maximum `quantity` that can be minted with {_mintERC2309}.
  // This limit is to prevent overflows on the address data entries.
  // For a limit of 5000, a total of 3.689e15 calls to {_mintERC2309}
  // is required to cause an overflow, which is unrealistic.
  uint256 private constant _MAX_MINT_ERC2309_QUANTITY_LIMIT = 5000;

  // The `Transfer` event signature is given by:
  // `keccak256(bytes("Transfer(address,address,uint256)"))`.
  bytes32 private constant _TRANSFER_EVENT_SIGNATURE =
    0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

  // =============================================================
  //                            STORAGE
  // =============================================================

  // The next token ID to be minted.
  uint256 internal _currentIndex;

  // The number of tokens burned.
  uint256 private _burnCounter;

  // Token name
  string private _name;

  // Token symbol
  string private _symbol;

  // Mapping from token ID to ownership details
  // An empty struct value does not necessarily mean the token is unowned.
  // See {_packedOwnershipOf} implementation for details.
  //
  // Bits Layout:
  // - [0..159]   `addr`
  // - [160..223] `startTimestamp`
  // - [224]      `burned`
  // - [225]      `nextInitialized`
  // - [232..255] `extraData`
  mapping(uint256 => uint256) internal _packedOwnerships;

  // Mapping owner address to address data.
  //
  // Bits Layout:
  // - [0..63]    `balance`
  // - [64..127]  `numberMinted`
  // - [128..191] `numberBurned`
  // - [192..255] `aux`
  mapping(address => uint256) internal _packedAddressData;

  // Mapping from token ID to approved address.
  mapping(uint256 => TokenApprovalRef) private _tokenApprovals;

  // Mapping from owner to operator approvals
  mapping(address => mapping(address => bool)) private _operatorApprovals;

  // =============================================================
  //                          CONSTRUCTOR
  // =============================================================

  constructor(string memory name_, string memory symbol_) {
    _name = name_;
    _symbol = symbol_;
    _currentIndex = _startTokenId();
  }

  // =============================================================
  //                   TOKEN COUNTING OPERATIONS
  // =============================================================

  /**
   * @dev Returns the starting token ID.
   * To change the starting token ID, please override this function.
   */
  function _startTokenId() internal view virtual returns (uint256) {
    return 0;
  }

  /**
   * @dev Returns the next token ID to be minted.
   */
  function _nextTokenId() internal view virtual returns (uint256) {
    return _currentIndex;
  }


  /**
   * @dev Returns the total number of tokens in existence.
   * Burned tokens will reduce the count.
   * To get the total number of tokens minted, please see {_totalMinted}.
   */
  function totalSupply() public view virtual override returns (uint256) {
    // Counter underflow is impossible as _burnCounter cannot be incremented
    // more than `_currentIndex - _startTokenId()` times.
    unchecked {
      return _currentIndex - _burnCounter - _startTokenId();
    }
  }

  /**
   * @dev Returns the total amount of tokens minted in the contract.
   */
  function _totalMinted() internal view virtual returns (uint256) {
    // Counter underflow is impossible as `_currentIndex` does not decrement,
    // and it is initialized to `_startTokenId()`.
    unchecked {
      return _currentIndex - _startTokenId();
    }
  }

  /**
   * @dev Returns the total number of tokens burned.
   */
  function _totalBurned() internal view virtual returns (uint256) {
    return _burnCounter;
  }

  // =============================================================
  //                    ADDRESS DATA OPERATIONS
  // =============================================================

  /**
   * @dev Returns the number of tokens in `owner`'s account.
   */
  function balanceOf(address owner)
    public
    view
    virtual
    override
    returns (uint256)
  {
    if (owner == address(0)) revert BalanceQueryForZeroAddress();
    return _packedAddressData[owner] & _BITMASK_ADDRESS_DATA_ENTRY;
  }

  /**
   * Returns the number of tokens minted by `owner`.
   */
  function _numberMinted(address owner) internal view returns (uint256) {
    return
      (_packedAddressData[owner] >> _BITPOS_NUMBER_MINTED) &
      _BITMASK_ADDRESS_DATA_ENTRY;
  }

  /**
   * Returns the number of tokens burned by or on behalf of `owner`.
   */
  function _numberBurned(address owner) internal view returns (uint256) {
    return
      (_packedAddressData[owner] >> _BITPOS_NUMBER_BURNED) &
      _BITMASK_ADDRESS_DATA_ENTRY;
  }

  /**
   * Returns the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).
   */
  function _getAux(address owner) internal view returns (uint64) {
    return uint64(_packedAddressData[owner] >> _BITPOS_AUX);
  }

  /**
   * Sets the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).
   * If there are multiple variables, please pack them into a uint64.
   */
  function _setAux(address owner, uint64 aux) internal virtual {
    uint256 packed = _packedAddressData[owner];
    uint256 auxCasted;
    // Cast `aux` with assembly to avoid redundant masking.
    assembly {
      auxCasted := aux
    }
    packed = (packed & _BITMASK_AUX_COMPLEMENT) | (auxCasted << _BITPOS_AUX);
    _packedAddressData[owner] = packed;
  }

  // =============================================================
  //                            IERC165
  // =============================================================

  /**
   * @dev Returns true if this contract implements the interface defined by
   * `interfaceId`. See the corresponding
   * [EIP section](https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified)
   * to learn more about how these ids are created.
   *
   * This function call must use less than 30000 gas.
   */
  function supportsInterface(bytes4 interfaceId)
    public
    view
    virtual
    override
    returns (bool)
  {
    // The interface IDs are constants representing the first 4 bytes
    // of the XOR of all function selectors in the interface.
    // See: [ERC165](https://eips.ethereum.org/EIPS/eip-165)
    // (e.g. `bytes4(i.functionA.selector ^ i.functionB.selector ^ ...)`)
    return
      interfaceId == 0x01ffc9a7 || // ERC165 interface ID for ERC165.
      interfaceId == 0x80ac58cd || // ERC165 interface ID for ERC721.
      interfaceId == 0x5b5e139f; // ERC165 interface ID for ERC721Metadata.
  }

  // =============================================================
  //                        IERC721Metadata
  // =============================================================

  /**
   * @dev Returns the token collection name.
   */
  function name() public view virtual override returns (string memory) {
    return _name;
  }

  /**
   * @dev Returns the token collection symbol.
   */
  function symbol() public view virtual override returns (string memory) {
    return _symbol;
  }

  /**
   * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
   */
  function tokenURI(uint256 tokenId)
    public
    view
    virtual
    override
    returns (string memory)
  {
    if (!_exists(tokenId)) revert URIQueryForNonexistentToken();

    string memory baseURI = _baseURI();
    return
      bytes(baseURI).length != 0
        ? string(abi.encodePacked(baseURI, _toString(tokenId)))
        : "";
  }

  /**
   * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
   * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
   * by default, it can be overridden in child contracts.
   */
  function _baseURI() internal view virtual returns (string memory) {
    return "";
  }

  /**
   * @dev Casts the address to uint256 without masking.
   */
  function _addressToUint256(address value)
    private
    pure
    returns (uint256 result)
  {
    assembly {
      result := value
    }
  }

  /**
   * @dev Casts the boolean to uint256 without branching.
   */
  function _boolToUint256(bool value) private pure returns (uint256 result) {
    assembly {
      result := value
    }
  }

  // =============================================================
  //                     OWNERSHIPS OPERATIONS
  // =============================================================

  /**
   * @dev Returns the owner of the `tokenId` token.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   */
  function ownerOf(uint256 tokenId)
    public
    view
    virtual
    override
    returns (address)
  {
    return address(uint160(_packedOwnershipOf(tokenId)));
  }

  /**
   * @dev Gas spent here starts off proportional to the maximum mint batch size.
   * It gradually moves to O(1) as tokens get transferred around over time.
   */
  function _ownershipOf(uint256 tokenId)
    internal
    view
    virtual
    returns (TokenOwnership memory)
  {
    return _unpackedOwnership(_packedOwnershipOf(tokenId));
  }

  /**
   * @dev Returns the unpacked `TokenOwnership` struct at `index`.
   */
  function _ownershipAt(uint256 index)
    internal
    view
    virtual
    returns (TokenOwnership memory)
  {
    return _unpackedOwnership(_packedOwnerships[index]);
  }

  /**
   * @dev Initializes the ownership slot minted at `index` for efficiency purposes.
   */
  function _initializeOwnershipAt(uint256 index) internal virtual {
    if (_packedOwnerships[index] == 0) {
      _packedOwnerships[index] = _packedOwnershipOf(index);
    }
  }

  /**
   * Returns the packed ownership data of `tokenId`.
   */
  function _packedOwnershipOf(uint256 tokenId) internal view returns (uint256) {
    uint256 curr = tokenId;

    unchecked {
      if (_startTokenId() <= curr)
        if (curr < _currentIndex) {
          uint256 packed = _packedOwnerships[curr];
          // If not burned.
          if (packed & _BITMASK_BURNED == 0) {
            // Invariant:
            // There will always be an initialized ownership slot
            // (i.e. `ownership.addr != address(0) && ownership.burned == false`)
            // before an unintialized ownership slot
            // (i.e. `ownership.addr == address(0) && ownership.burned == false`)
            // Hence, `curr` will not underflow.
            //
            // We can directly compare the packed value.
            // If the address is zero, packed will be zero.
            while (packed == 0) {
              packed = _packedOwnerships[--curr];
            }
            return packed;
          }
        }
    }
    revert OwnerQueryForNonexistentToken();
  }

  /**
   * @dev Returns the unpacked `TokenOwnership` struct from `packed`.
   */
  function _unpackedOwnership(uint256 packed)
    private
    pure
    returns (TokenOwnership memory ownership)
  {
    ownership.addr = address(uint160(packed));
    ownership.startTimestamp = uint64(packed >> _BITPOS_START_TIMESTAMP);
    ownership.burned = packed & _BITMASK_BURNED != 0;
    ownership.extraData = uint24(packed >> _BITPOS_EXTRA_DATA);
  }

  /**
   * @dev Packs ownership data into a single uint256.
   */
  function _packOwnershipData(address owner, uint256 flags)
    internal
    view
    returns (uint256 result)
  {
    assembly {
      // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.
      owner := and(owner, _BITMASK_ADDRESS)
      // `owner | (block.timestamp << _BITPOS_START_TIMESTAMP) | flags`.
      result := or(owner, or(shl(_BITPOS_START_TIMESTAMP, timestamp()), flags))
    }
  }

  /**
   * @dev Returns the `nextInitialized` flag set if `quantity` equals 1.
   */
  function _nextInitializedFlag(uint256 quantity)
    private
    pure
    returns (uint256 result)
  {
    // For branchless setting of the `nextInitialized` flag.
    assembly {
      // `(quantity == 1) << _BITPOS_NEXT_INITIALIZED`.
      result := shl(_BITPOS_NEXT_INITIALIZED, eq(quantity, 1))
    }
  }

  // =============================================================
  //                      APPROVAL OPERATIONS
  // =============================================================

  /**
   * @dev Gives permission to `to` to transfer `tokenId` token to another account.
   * The approval is cleared when the token is transferred.
   *
   * Only a single account can be approved at a time, so approving the
   * zero address clears previous approvals.
   *
   * Requirements:
   *
   * - The caller must own the token or be an approved operator.
   * - `tokenId` must exist.
   *
   * Emits an {Approval} event.
   */
  function approve(address to, uint256 tokenId) public virtual override {
    address owner = ownerOf(tokenId);

    if (_msgSenderERC721A() != owner)
      if (!isApprovedForAll(owner, _msgSenderERC721A())) {
        revert ApprovalCallerNotOwnerNorApproved();
      }

    _tokenApprovals[tokenId].value = to;
    emit Approval(owner, to, tokenId);
  }

  /**
   * @dev Returns the account approved for `tokenId` token.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   */
  function getApproved(uint256 tokenId)
    public
    view
    virtual
    override
    returns (address)
  {
    if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();

    return _tokenApprovals[tokenId].value;
  }

  /**
   * @dev Approve or remove `operator` as an operator for the caller.
   * Operators can call {transferFrom} or {safeTransferFrom}
   * for any token owned by the caller.
   *
   * Requirements:
   *
   * - The `operator` cannot be the caller.
   *
   * Emits an {ApprovalForAll} event.
   */
  function setApprovalForAll(address operator, bool approved)
    public
    virtual
    override
  {
    if (operator == _msgSenderERC721A()) revert ApproveToCaller();

    _operatorApprovals[_msgSenderERC721A()][operator] = approved;
    emit ApprovalForAll(_msgSenderERC721A(), operator, approved);
  }

  /**
   * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
   *
   * See {setApprovalForAll}.
   */
  function isApprovedForAll(address owner, address operator)
    public
    view
    virtual
    override
    returns (bool)
  {
    return _operatorApprovals[owner][operator];
  }

  /**
   * @dev Returns whether `tokenId` exists.
   *
   * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
   *
   * Tokens start existing when they are minted. See {_mint}.
   */
  function _exists(uint256 tokenId) internal view virtual returns (bool) {
    return
      _startTokenId() <= tokenId &&
      tokenId < _currentIndex && // If within bounds,
      _packedOwnerships[tokenId] & _BITMASK_BURNED == 0; // and not burned.
  }

  /**
   * @dev Returns whether `msgSender` is equal to `approvedAddress` or `owner`.
   */
  function _isSenderApprovedOrOwner(
    address approvedAddress,
    address owner,
    address msgSender
  ) internal pure returns (bool result) {
    assembly {
      // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.
      owner := and(owner, _BITMASK_ADDRESS)
      // Mask `msgSender` to the lower 160 bits, in case the upper bits somehow aren't clean.
      msgSender := and(msgSender, _BITMASK_ADDRESS)
      // `msgSender == owner || msgSender == approvedAddress`.
      result := or(eq(msgSender, owner), eq(msgSender, approvedAddress))
    }
  }

  /**
   * @dev Returns the storage slot and value for the approved address of `tokenId`.
   */
  function _getApprovedSlotAndAddress(uint256 tokenId)
    internal
    view
    returns (uint256 approvedAddressSlot, address approvedAddress)
  {
    TokenApprovalRef storage tokenApproval = _tokenApprovals[tokenId];
    // The following is equivalent to `approvedAddress = _tokenApprovals[tokenId].value`.
    assembly {
      approvedAddressSlot := tokenApproval.slot
      approvedAddress := sload(approvedAddressSlot)
    }
  }

  // =============================================================
  //                      TRANSFER OPERATIONS
  // =============================================================

  /**
   * @dev Transfers `tokenId` from `from` to `to`.
   *
   * Requirements:
   *
   * - `from` cannot be the zero address.
   * - `to` cannot be the zero address.
   * - `tokenId` token must be owned by `from`.
   * - If the caller is not `from`, it must be approved to move this token
   * by either {approve} or {setApprovalForAll}.
   *
   * Emits a {Transfer} event.
   */
  function transferFrom(
    address from,
    address to,
    uint256 tokenId
  ) public virtual override {
    uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

    if (address(uint160(prevOwnershipPacked)) != from)
      revert TransferFromIncorrectOwner();

    (
      uint256 approvedAddressSlot,
      address approvedAddress
    ) = _getApprovedSlotAndAddress(tokenId);

    // The nested ifs save around 20+ gas over a compound boolean condition.
    if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))
      if (!isApprovedForAll(from, _msgSenderERC721A()))
        revert TransferCallerNotOwnerNorApproved();

    if (to == address(0)) revert TransferToZeroAddress();

    _beforeTokenTransfers(from, to, tokenId, 1);

    // Clear approvals from the previous owner.
    assembly {
      if approvedAddress {
        // This is equivalent to `delete _tokenApprovals[tokenId]`.
        sstore(approvedAddressSlot, 0)
      }
    }

    // Underflow of the sender's balance is impossible because we check for
    // ownership above and the recipient's balance can't realistically overflow.
    // Counter overflow is incredibly unrealistic as `tokenId` would have to be 2**256.
    unchecked {
      // We can directly increment and decrement the balances.
      --_packedAddressData[from]; // Updates: `balance -= 1`.
      ++_packedAddressData[to]; // Updates: `balance += 1`.

      // Updates:
      // - `address` to the next owner.
      // - `startTimestamp` to the timestamp of transfering.
      // - `burned` to `false`.
      // - `nextInitialized` to `true`.
      _packedOwnerships[tokenId] = _packOwnershipData(
        to,
        _BITMASK_NEXT_INITIALIZED |
          _nextExtraData(from, to, prevOwnershipPacked)
      );

      // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
      if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {
        uint256 nextTokenId = tokenId + 1;
        // If the next slot's address is zero and not burned (i.e. packed value is zero).
        if (_packedOwnerships[nextTokenId] == 0) {
          // If the next slot is within bounds.
          if (nextTokenId != _currentIndex) {
            // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
            _packedOwnerships[nextTokenId] = prevOwnershipPacked;
          }
        }
      }
    }

    emit Transfer(from, to, tokenId);
    _afterTokenTransfers(from, to, tokenId, 1);
  }

  /**
   * @dev Equivalent to `safeTransferFrom(from, to, tokenId, '')`.
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId
  ) public virtual override {
    safeTransferFrom(from, to, tokenId, "");
  }

  /**
   * @dev Safely transfers `tokenId` token from `from` to `to`.
   *
   * Requirements:
   *
   * - `from` cannot be the zero address.
   * - `to` cannot be the zero address.
   * - `tokenId` token must exist and be owned by `from`.
   * - If the caller is not `from`, it must be approved to move this token
   * by either {approve} or {setApprovalForAll}.
   * - If `to` refers to a smart contract, it must implement
   * {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
   *
   * Emits a {Transfer} event.
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) public virtual override {
    transferFrom(from, to, tokenId);
    if (to.code.length != 0)
      if (!_checkContractOnERC721Received(from, to, tokenId, _data)) {
        revert TransferToNonERC721ReceiverImplementer();
      }
  }

  /**
   * @dev Hook that is called before a set of serially-ordered token IDs
   * are about to be transferred. This includes minting.
   * And also called before burning one token.
   *
   * `startTokenId` - the first token ID to be transferred.
   * `quantity` - the amount to be transferred.
   *
   * Calling conditions:
   *
   * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
   * transferred to `to`.
   * - When `from` is zero, `tokenId` will be minted for `to`.
   * - When `to` is zero, `tokenId` will be burned by `from`.
   * - `from` and `to` are never both zero.
   */
  function _beforeTokenTransfers(
    address from,
    address to,
    uint256 startTokenId,
    uint256 quantity
  ) internal virtual {}

  /**
   * @dev Hook that is called after a set of serially-ordered token IDs
   * have been transferred. This includes minting.
   * And also called after one token has been burned.
   *
   * `startTokenId` - the first token ID to be transferred.
   * `quantity` - the amount to be transferred.
   *
   * Calling conditions:
   *
   * - When `from` and `to` are both non-zero, `from`'s `tokenId` has been
   * transferred to `to`.
   * - When `from` is zero, `tokenId` has been minted for `to`.
   * - When `to` is zero, `tokenId` has been burned by `from`.
   * - `from` and `to` are never both zero.
   */
  function _afterTokenTransfers(
    address from,
    address to,
    uint256 startTokenId,
    uint256 quantity
  ) internal virtual {}

  /**
   * @dev Private function to invoke {IERC721Receiver-onERC721Received} on a target contract.
   *
   * `from` - Previous owner of the given token ID.
   * `to` - Target address that will receive the token.
   * `tokenId` - Token ID to be transferred.
   * `_data` - Optional data to send along with the call.
   *
   * Returns whether the call correctly returned the expected magic value.
   */
  function _checkContractOnERC721Received(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) private returns (bool) {
    try
      ERC721A__IERC721Receiver(to).onERC721Received(
        _msgSenderERC721A(),
        from,
        tokenId,
        _data
      )
    returns (bytes4 retval) {
      return retval == ERC721A__IERC721Receiver(to).onERC721Received.selector;
    } catch (bytes memory reason) {
      if (reason.length == 0) {
        revert TransferToNonERC721ReceiverImplementer();
      } else {
        assembly {
          revert(add(32, reason), mload(reason))
        }
      }
    }
  }

  // =============================================================
  //                        MINT OPERATIONS
  // =============================================================

  /**
   * @dev Mints `quantity` tokens and transfers them to `to`.
   *
   * Requirements:
   *
   * - `to` cannot be the zero address.
   * - `quantity` must be greater than 0.
   *
   * Emits a {Transfer} event for each mint.
   */
  function _mint(address to, uint256 quantity) internal virtual {
    uint256 startTokenId = _currentIndex;
    if (quantity == 0) revert MintZeroQuantity();

    _beforeTokenTransfers(address(0), to, startTokenId, quantity);

    // Overflows are incredibly unrealistic.
    // `balance` and `numberMinted` have a maximum limit of 2**64.
    // `tokenId` has a maximum limit of 2**256.
    unchecked {
      // Updates:
      // - `balance += quantity`.
      // - `numberMinted += quantity`.
      //
      // We can directly add to the `balance` and `numberMinted`.
      _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);

      // Updates:
      // - `address` to the owner.
      // - `startTimestamp` to the timestamp of minting.
      // - `burned` to `false`.
      // - `nextInitialized` to `quantity == 1`.
      _packedOwnerships[startTokenId] = _packOwnershipData(
        to,
        _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
      );

      uint256 toMasked;
      uint256 end = startTokenId + quantity;

      // Use assembly to loop and emit the `Transfer` event for gas savings.
      // The duplicated `log4` removes an extra check and reduces stack juggling.
      // The assembly, together with the surrounding Solidity code, have been
      // delicately arranged to nudge the compiler into producing optimized opcodes.
      assembly {
        // Mask `to` to the lower 160 bits, in case the upper bits somehow aren't clean.
        toMasked := and(to, _BITMASK_ADDRESS)
        // Emit the `Transfer` event.
        log4(
          0, // Start of data (0, since no data).
          0, // End of data (0, since no data).
          _TRANSFER_EVENT_SIGNATURE, // Signature.
          0, // `address(0)`.
          toMasked, // `to`.
          startTokenId // `tokenId`.
        )

        for {
          let tokenId := add(startTokenId, 1)
        } iszero(eq(tokenId, end)) {
          tokenId := add(tokenId, 1)
        } {
          // Emit the `Transfer` event. Similar to above.
          log4(0, 0, _TRANSFER_EVENT_SIGNATURE, 0, toMasked, tokenId)
        }
      }
      if (toMasked == 0) revert MintToZeroAddress();

      _currentIndex = end;
    }
    _afterTokenTransfers(address(0), to, startTokenId, quantity);
  }

  /**
   * @dev Mints `quantity` tokens and transfers them to `to`.
   *
   * This function is intended for efficient minting only during contract creation.
   *
   * It emits only one {ConsecutiveTransfer} as defined in
   * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
   * instead of a sequence of {Transfer} event(s).
   *
   * Calling this function outside of contract creation WILL make your contract
   * non-compliant with the ERC721 standard.
   * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
   * {ConsecutiveTransfer} event is only permissible during contract creation.
   *
   * Requirements:
   *
   * - `to` cannot be the zero address.
   * - `quantity` must be greater than 0.
   *
   * Emits a {ConsecutiveTransfer} event.
   */
  function _mintERC2309(address to, uint256 quantity) internal virtual {
    uint256 startTokenId = _currentIndex;
    if (to == address(0)) revert MintToZeroAddress();
    if (quantity == 0) revert MintZeroQuantity();
    if (quantity > _MAX_MINT_ERC2309_QUANTITY_LIMIT)
      revert MintERC2309QuantityExceedsLimit();

    _beforeTokenTransfers(address(0), to, startTokenId, quantity);

    // Overflows are unrealistic due to the above check for `quantity` to be below the limit.
    unchecked {
      // Updates:
      // - `balance += quantity`.
      // - `numberMinted += quantity`.
      //
      // We can directly add to the `balance` and `numberMinted`.
      _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);

      // Updates:
      // - `address` to the owner.
      // - `startTimestamp` to the timestamp of minting.
      // - `burned` to `false`.
      // - `nextInitialized` to `quantity == 1`.
      _packedOwnerships[startTokenId] = _packOwnershipData(
        to,
        _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)
      );

      emit ConsecutiveTransfer(
        startTokenId,
        startTokenId + quantity - 1,
        address(0),
        to
      );

      _currentIndex = startTokenId + quantity;
    }
    _afterTokenTransfers(address(0), to, startTokenId, quantity);
  }

  /**
   * @dev Safely mints `quantity` tokens and transfers them to `to`.
   *
   * Requirements:
   *
   * - If `to` refers to a smart contract, it must implement
   * {IERC721Receiver-onERC721Received}, which is called for each safe transfer.
   * - `quantity` must be greater than 0.
   *
   * See {_mint}.
   *
   * Emits a {Transfer} event for each mint.
   */
  function _safeMint(
    address to,
    uint256 quantity,
    bytes memory _data
  ) internal virtual {
    _mint(to, quantity);

    unchecked {
      if (to.code.length != 0) {
        uint256 end = _currentIndex;
        uint256 index = end - quantity;
        do {
          if (!_checkContractOnERC721Received(address(0), to, index++, _data)) {
            revert TransferToNonERC721ReceiverImplementer();
          }
        } while (index < end);
        // Reentrancy protection.
        if (_currentIndex != end) revert();
      }
    }
  }

  /**
   * @dev Equivalent to `_safeMint(to, quantity, '')`.
   */
  function _safeMint(address to, uint256 quantity) internal virtual {
    _safeMint(to, quantity, "");
  }

  // =============================================================
  //                        BURN OPERATIONS
  // =============================================================

  /**
   * @dev Equivalent to `_burn(tokenId, false)`.
   */
  function _burn(uint256 tokenId) internal virtual {
    _burn(tokenId, false);
  }

  /**
   * @dev Destroys `tokenId`.
   * The approval is cleared when the token is burned.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   *
   * Emits a {Transfer} event.
   */
  function _burn(uint256 tokenId, bool approvalCheck) internal virtual {
    uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

    address from = address(uint160(prevOwnershipPacked));

    (
      uint256 approvedAddressSlot,
      address approvedAddress
    ) = _getApprovedSlotAndAddress(tokenId);

    if (approvalCheck) {
      // The nested ifs save around 20+ gas over a compound boolean condition.
      if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))
        if (!isApprovedForAll(from, _msgSenderERC721A()))
          revert TransferCallerNotOwnerNorApproved();
    }

    _beforeTokenTransfers(from, address(0), tokenId, 1);

    // Clear approvals from the previous owner.
    assembly {
      if approvedAddress {
        // This is equivalent to `delete _tokenApprovals[tokenId]`.
        sstore(approvedAddressSlot, 0)
      }
    }

    // Underflow of the sender's balance is impossible because we check for
    // ownership above and the recipient's balance can't realistically overflow.
    // Counter overflow is incredibly unrealistic as `tokenId` would have to be 2**256.
    unchecked {
      // Updates:
      // - `balance -= 1`.
      // - `numberBurned += 1`.
      //
      // We can directly decrement the balance, and increment the number burned.
      // This is equivalent to `packed -= 1; packed += 1 << _BITPOS_NUMBER_BURNED;`.
      _packedAddressData[from] += (1 << _BITPOS_NUMBER_BURNED) - 1;

      // Updates:
      // - `address` to the last owner.
      // - `startTimestamp` to the timestamp of burning.
      // - `burned` to `true`.
      // - `nextInitialized` to `true`.
      _packedOwnerships[tokenId] = _packOwnershipData(
        from,
        (_BITMASK_BURNED | _BITMASK_NEXT_INITIALIZED) |
          _nextExtraData(from, address(0), prevOwnershipPacked)
      );

      // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
      if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {
        uint256 nextTokenId = tokenId + 1;
        // If the next slot's address is zero and not burned (i.e. packed value is zero).
        if (_packedOwnerships[nextTokenId] == 0) {
          // If the next slot is within bounds.
          if (nextTokenId != _currentIndex) {
            // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
            _packedOwnerships[nextTokenId] = prevOwnershipPacked;
          }
        }
      }
    }

    emit Transfer(from, address(0), tokenId);
    _afterTokenTransfers(from, address(0), tokenId, 1);

    // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.
    unchecked {
      _burnCounter++;
    }
  }

  // =============================================================
  //                     EXTRA DATA OPERATIONS
  // =============================================================

  /**
   * @dev Directly sets the extra data for the ownership data `index`.
   */
  function _setExtraDataAt(uint256 index, uint24 extraData) internal virtual {
    uint256 packed = _packedOwnerships[index];
    if (packed == 0) revert OwnershipNotInitializedForExtraData();
    uint256 extraDataCasted;
    // Cast `extraData` with assembly to avoid redundant masking.
    assembly {
      extraDataCasted := extraData
    }
    packed =
      (packed & _BITMASK_EXTRA_DATA_COMPLEMENT) |
      (extraDataCasted << _BITPOS_EXTRA_DATA);
    _packedOwnerships[index] = packed;
  }

  /**
   * @dev Called during each token transfer to set the 24bit `extraData` field.
   * Intended to be overridden by the cosumer contract.
   *
   * `previousExtraData` - the value of `extraData` before transfer.
   *
   * Calling conditions:
   *
   * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
   * transferred to `to`.
   * - When `from` is zero, `tokenId` will be minted for `to`.
   * - When `to` is zero, `tokenId` will be burned by `from`.
   * - `from` and `to` are never both zero.
   */
  function _extraData(
    address from,
    address to,
    uint24 previousExtraData
  ) internal view virtual returns (uint24) {}

  /**
   * @dev Returns the next extra data for the packed ownership data.
   * The returned result is shifted into position.
   */
  function _nextExtraData(
    address from,
    address to,
    uint256 prevOwnershipPacked
  ) internal view returns (uint256) {
    uint24 extraData = uint24(prevOwnershipPacked >> _BITPOS_EXTRA_DATA);
    return uint256(_extraData(from, to, extraData)) << _BITPOS_EXTRA_DATA;
  }

  // =============================================================
  //                       OTHER OPERATIONS
  // =============================================================

  /**
   * @dev Returns the message sender (defaults to `msg.sender`).
   *
   * If you are writing GSN compatible contracts, you need to override this function.
   */
  function _msgSenderERC721A() internal view virtual returns (address) {
    return msg.sender;
  }

  /**
   * @dev Converts a uint256 to its ASCII string decimal representation.
   */
  function _toString(uint256 value)
    internal
    pure
    virtual
    returns (string memory str)
  {
    assembly {
      // The maximum value of a uint256 contains 78 digits (1 byte per digit),
      // but we allocate 0x80 bytes to keep the free memory pointer 32-byte word aligned.
      // We will need 1 32-byte word to store the length,
      // and 3 32-byte words to store a maximum of 78 digits. Total: 0x20 + 3 * 0x20 = 0x80.
      str := add(mload(0x40), 0x80)
      // Update the free memory pointer to allocate.
      mstore(0x40, str)

      // Cache the end of the memory to calculate the length later.
      let end := str

      // We write the string from rightmost digit to leftmost digit.
      // The following is essentially a do-while loop that also handles the zero case.
      // prettier-ignore
      for { let temp := value } 1 {} {
                str := sub(str, 1)
                // Write the character to the pointer.
                // The ASCII index of the '0' character is 48.
                mstore8(str, add(48, mod(temp, 10)))
                // Keep dividing `temp` until zero.
                temp := div(temp, 10)
                // prettier-ignore
                if iszero(temp) { break }
            }

      let length := sub(end, str)
      // Move the pointer 32 bytes leftwards to make room for the length.
      str := sub(str, 0x20)
      // Store the length.
      mstore(str, length)
    }
  }
}

File 8 of 17 : IERC721A.sol
// SPDX-License-Identifier: MIT
// ERC721A Contracts v4.2.2

pragma solidity ^0.8.4;

/**
 * @dev Interface of ERC721A.
 */
interface IERC721A {
  /**
   * The caller must own the token or be an approved operator.
   */
  error ApprovalCallerNotOwnerNorApproved();

  /**
   * The token does not exist.
   */
  error ApprovalQueryForNonexistentToken();

  /**
   * The caller cannot approve to their own address.
   */
  error ApproveToCaller();

  /**
   * Cannot query the balance for the zero address.
   */
  error BalanceQueryForZeroAddress();

  /**
   * Cannot mint to the zero address.
   */
  error MintToZeroAddress();

  /**
   * The quantity of tokens minted must be more than zero.
   */
  error MintZeroQuantity();

  /**
   * The token does not exist.
   */
  error OwnerQueryForNonexistentToken();

  /**
   * The caller must own the token or be an approved operator.
   */
  error TransferCallerNotOwnerNorApproved();

  /**
   * The token must be owned by `from`.
   */
  error TransferFromIncorrectOwner();

  /**
   * Cannot safely transfer to a contract that does not implement the
   * ERC721Receiver interface.
   */
  error TransferToNonERC721ReceiverImplementer();

  /**
   * Cannot transfer to the zero address.
   */
  error TransferToZeroAddress();

  /**
   * The token does not exist.
   */
  error URIQueryForNonexistentToken();

  /**
   * The `quantity` minted with ERC2309 exceeds the safety limit.
   */
  error MintERC2309QuantityExceedsLimit();

  /**
   * The `extraData` cannot be set on an unintialized ownership slot.
   */
  error OwnershipNotInitializedForExtraData();

  // =============================================================
  //                            STRUCTS
  // =============================================================

  struct TokenOwnership {
    // The address of the owner.
    address addr;
    // Stores the start time of ownership with minimal overhead for tokenomics.
    uint64 startTimestamp;
    // Whether the token has been burned.
    bool burned;
    // Arbitrary data similar to `startTimestamp` that can be set via {_extraData}.
    uint24 extraData;
  }

  // =============================================================
  //                         TOKEN COUNTERS
  // =============================================================

  /**
   * @dev Returns the total number of tokens in existence.
   * Burned tokens will reduce the count.
   * To get the total number of tokens minted, please see {_totalMinted}.
   */
  function totalSupply() external view returns (uint256);

  // =============================================================
  //                            IERC165
  // =============================================================

  /**
   * @dev Returns true if this contract implements the interface defined by
   * `interfaceId`. See the corresponding
   * [EIP section](https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified)
   * to learn more about how these ids are created.
   *
   * This function call must use less than 30000 gas.
   */
  function supportsInterface(bytes4 interfaceId) external view returns (bool);

  // =============================================================
  //                            IERC721
  // =============================================================

  /**
   * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
   */
  event Transfer(
    address indexed from,
    address indexed to,
    uint256 indexed tokenId
  );

  /**
   * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
   */
  event Approval(
    address indexed owner,
    address indexed approved,
    uint256 indexed tokenId
  );

  /**
   * @dev Emitted when `owner` enables or disables
   * (`approved`) `operator` to manage all of its assets.
   */
  event ApprovalForAll(
    address indexed owner,
    address indexed operator,
    bool approved
  );

  /**
   * @dev Returns the number of tokens in `owner`'s account.
   */
  function balanceOf(address owner) external view returns (uint256 balance);

  /**
   * @dev Returns the owner of the `tokenId` token.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   */
  function ownerOf(uint256 tokenId) external view returns (address owner);

  /**
   * @dev Safely transfers `tokenId` token from `from` to `to`,
   * checking first that contract recipients are aware of the ERC721 protocol
   * to prevent tokens from being forever locked.
   *
   * Requirements:
   *
   * - `from` cannot be the zero address.
   * - `to` cannot be the zero address.
   * - `tokenId` token must exist and be owned by `from`.
   * - If the caller is not `from`, it must be have been allowed to move
   * this token by either {approve} or {setApprovalForAll}.
   * - If `to` refers to a smart contract, it must implement
   * {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
   *
   * Emits a {Transfer} event.
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes calldata data
  ) external;

  /**
   * @dev Equivalent to `safeTransferFrom(from, to, tokenId, '')`.
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId
  ) external;

  /**
   * @dev Transfers `tokenId` from `from` to `to`.
   *
   * WARNING: Usage of this method is discouraged, use {safeTransferFrom}
   * whenever possible.
   *
   * Requirements:
   *
   * - `from` cannot be the zero address.
   * - `to` cannot be the zero address.
   * - `tokenId` token must be owned by `from`.
   * - If the caller is not `from`, it must be approved to move this token
   * by either {approve} or {setApprovalForAll}.
   *
   * Emits a {Transfer} event.
   */
  function transferFrom(
    address from,
    address to,
    uint256 tokenId
  ) external;

  /**
   * @dev Gives permission to `to` to transfer `tokenId` token to another account.
   * The approval is cleared when the token is transferred.
   *
   * Only a single account can be approved at a time, so approving the
   * zero address clears previous approvals.
   *
   * Requirements:
   *
   * - The caller must own the token or be an approved operator.
   * - `tokenId` must exist.
   *
   * Emits an {Approval} event.
   */
  function approve(address to, uint256 tokenId) external;

  /**
   * @dev Approve or remove `operator` as an operator for the caller.
   * Operators can call {transferFrom} or {safeTransferFrom}
   * for any token owned by the caller.
   *
   * Requirements:
   *
   * - The `operator` cannot be the caller.
   *
   * Emits an {ApprovalForAll} event.
   */
  function setApprovalForAll(address operator, bool _approved) external;

  /**
   * @dev Returns the account approved for `tokenId` token.
   *
   * Requirements:
   *
   * - `tokenId` must exist.
   */
  function getApproved(uint256 tokenId)
    external
    view
    returns (address operator);

  /**
   * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
   *
   * See {setApprovalForAll}.
   */
  function isApprovedForAll(address owner, address operator)
    external
    view
    returns (bool);

  // =============================================================
  //                        IERC721Metadata
  // =============================================================

  /**
   * @dev Returns the token collection name.
   */
  function name() external view returns (string memory);

  /**
   * @dev Returns the token collection symbol.
   */
  function symbol() external view returns (string memory);

  /**
   * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
   */
  function tokenURI(uint256 tokenId) external view returns (string memory);

  // =============================================================
  //                           IERC2309
  // =============================================================

  /**
   * @dev Emitted when tokens in `fromTokenId` to `toTokenId`
   * (inclusive) is transferred from `from` to `to`, as defined in the
   * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309) standard.
   *
   * See {_mintERC2309} for more details.
   */
  event ConsecutiveTransfer(
    uint256 indexed fromTokenId,
    uint256 toTokenId,
    address indexed from,
    address indexed to
  );
}

File 9 of 17 : IStableToken.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

interface IStableToken {
    function allowance(address owner, address spender) external returns (uint);
    function transferFrom(address sender, address recipient, uint256 amount) external;
}

File 10 of 17 : Address.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.4;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                /// @solidity memory-safe-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

File 11 of 17 : Context.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.4;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

File 12 of 17 : ECDSA.sol
//SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

library ECDSA {

  /**
   * @dev Recover signer address from a message by using their signature
   * @param hash bytes32 message, the hash is the signed message. What is recovered is the signer address.
   * @param signature bytes signature, the signature is generated using web3.eth.sign()
   */
  function recover(bytes32 hash, bytes memory signature)
    internal
    pure
    returns (address)
  {
    bytes32 r;
    bytes32 s;
    uint8 v;

    // Check the signature length
    if (signature.length != 65) {
      return (address(0));
    }

    // Divide the signature in r, s and v variables with inline assembly.
    assembly {
      r := mload(add(signature, 0x20))
      s := mload(add(signature, 0x40))
      v := byte(0, mload(add(signature, 0x60)))
    }

    // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
    if (v < 27) {
      v += 27;
    }

    // If the version is correct return the signer address
    if (v != 27 && v != 28) {
      return (address(0));
    } else {
      // solium-disable-next-line arg-overflow
      return ecrecover(hash, v, r, s);
    }
  }

  /**
    * toEthSignedMessageHash
    * @dev prefix a bytes32 value with "\x19Ethereum Signed Message:"
    * and hash the result
    */
  function toEthSignedMessageHash(bytes32 hash)
    internal
    pure
    returns (bytes32)
  {
    return keccak256(
      abi.encodePacked("\x19Ethereum Signed Message:\n32", hash)
    );
  }
}

File 13 of 17 : EnumerableSet.sol
// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 *
 * [WARNING]
 * ====
 * Trying to delete such a structure from storage will likely result in data corruption, rendering the structure
 * unusable.
 * See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
 *
 * In order to clean an EnumerableSet, you can either remove all elements one by one or create a fresh instance using an
 * array of EnumerableSet.
 * ====
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping(bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) {
            // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            if (lastIndex != toDeleteIndex) {
                bytes32 lastValue = set._values[lastIndex];

                // Move the last value to the index where the value to delete is
                set._values[toDeleteIndex] = lastValue;
                // Update the index for the moved value
                set._indexes[lastValue] = valueIndex; // Replace lastValue's index to valueIndex
            }

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        return set._values[index];
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function _values(Set storage set) private view returns (bytes32[] memory) {
        return set._values;
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
        bytes32[] memory store = _values(set._inner);
        bytes32[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(AddressSet storage set) internal view returns (address[] memory) {
        bytes32[] memory store = _values(set._inner);
        address[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }

    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(UintSet storage set) internal view returns (uint256[] memory) {
        bytes32[] memory store = _values(set._inner);
        uint256[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }
}

File 14 of 17 : Operator.sol
// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

import "./EnumerableSet.sol";

abstract contract Operator {
    using EnumerableSet for EnumerableSet.AddressSet;
    EnumerableSet.AddressSet private OPERATOR;

    modifier onlyOperator() {
        require(OPERATOR.contains(msg.sender), "NOT OPERATOR.");
        _;
    }

    constructor() internal {
        OPERATOR.add(msg.sender);
    }

    function getOperator() external view returns (address[] memory) {
        return OPERATOR.values();
    }

    function updateOperator(address _operatorAddr, bool _flag) public onlyOperator {
        require(_operatorAddr != address(0), "ZERO ADDRESS.");
        if (_flag) {
            OPERATOR.add(_operatorAddr);
        } else {
            OPERATOR.remove(_operatorAddr);
        }
    }
}

File 15 of 17 : Ownable.sol
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.4;

import "./Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

File 16 of 17 : SafeMath.sol
// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b)
        internal
        pure
        returns (bool, uint256)
    {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

File 17 of 17 : TransferHelper.sol
// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
  function safeApprove(
    address token,
    address to,
    uint256 value
  ) internal {
    // bytes4(keccak256(bytes('approve(address,uint256)')));
    (bool success, bytes memory data) = token.call(
      abi.encodeWithSelector(0x095ea7b3, to, value)
    );
    require(
      success && (data.length == 0 || abi.decode(data, (bool))),
      "TransferHelper: APPROVE_FAILED"
    );
  }

  function safeTransfer(
    address token,
    address to,
    uint256 value
  ) internal {
    // bytes4(keccak256(bytes('transfer(address,uint256)')));
    (bool success, bytes memory data) = token.call(
      abi.encodeWithSelector(0xa9059cbb, to, value)
    );
    require(
      success && (data.length == 0 || abi.decode(data, (bool))),
      "TransferHelper: TRANSFER_FAILED"
    );
  }

  function safeTransferFrom(
    address token,
    address from,
    address to,
    uint256 value
  ) internal {
    // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
    (bool success, bytes memory data) = token.call(
      abi.encodeWithSelector(0x23b872dd, from, to, value)
    );
    require(
      success && (data.length == 0 || abi.decode(data, (bool))),
      "TransferHelper: TRANSFER_FROM_FAILED"
    );
  }

  function safeTransferETH(address to, uint256 value) internal {
    (bool success, ) = to.call{ value: value }(new bytes(0));
    require(success, "TransferHelper: ETH_TRANSFER_FAILED");
  }
}

Settings
{
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "devdoc",
        "userdoc",
        "metadata",
        "abi"
      ]
    }
  },
  "metadata": {
    "useLiteralContent": true
  },
  "libraries": {}
}

Contract ABI

[{"inputs":[],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address[3]","name":"addrs","type":"address[3]"},{"indexed":false,"internalType":"uint256","name":"tokenId","type":"uint256"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"AcceptOfferNFT","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address[3]","name":"addrs","type":"address[3]"},{"indexed":false,"internalType":"uint256","name":"tokenId","type":"uint256"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"AuctionNFT","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address[3]","name":"addrs","type":"address[3]"},{"indexed":false,"internalType":"uint256","name":"tokenId","type":"uint256"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"BuyNFTETH","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address[3]","name":"addrs","type":"address[3]"},{"indexed":false,"internalType":"uint256","name":"tokenId","type":"uint256"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"BuyNFTNormal","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"previousOwner","type":"address"},{"indexed":true,"internalType":"address","name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"inputs":[{"internalType":"address[6]","name":"_tradeAddress","type":"address[6]"},{"internalType":"uint256[4]","name":"_attributes","type":"uint256[4]"},{"internalType":"uint256","name":"nonce","type":"uint256"},{"internalType":"bytes","name":"signature","type":"bytes"}],"name":"acceptOfferNFT","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address[6]","name":"_tradeAddress","type":"address[6]"},{"internalType":"uint256[4]","name":"_attributes","type":"uint256[4]"}],"name":"auctionNFT","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address[6]","name":"_tradeAddress","type":"address[6]"},{"internalType":"uint256[4]","name":"_attributes","type":"uint256[4]"},{"internalType":"uint256","name":"nonce","type":"uint256"},{"internalType":"bytes","name":"signature","type":"bytes"}],"name":"buyNFTETH","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address[6]","name":"_tradeAddress","type":"address[6]"},{"internalType":"uint256[4]","name":"_attributes","type":"uint256[4]"},{"internalType":"uint256","name":"nonce","type":"uint256"},{"internalType":"bytes","name":"signature","type":"bytes"}],"name":"buyNFTNormal","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"getOperator","outputs":[{"internalType":"address[]","name":"","type":"address[]"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"owner","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"renounceOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"_address","type":"address"},{"internalType":"bool","name":"approved","type":"bool"}],"name":"setWhitelistAddress","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"_address","type":"address"},{"internalType":"bool","name":"approved","type":"bool"}],"name":"setWhitelistNFTAddress","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"_operatorAddr","type":"address"},{"internalType":"bool","name":"_flag","type":"bool"}],"name":"updateOperator","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"whitelistAddress","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"whitelistNFTAddress","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"}]

Deployed Bytecode

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A contract address hosts a smart contract, which is a set of code stored on the blockchain that runs when predetermined conditions are met. Learn more about addresses in our Knowledge Base.