// File: @openzeppelin/contracts/access/Ownable.sol



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

pragma solidity ^0.8.0;

import "../utils/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: @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol



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

pragma solidity ^0.8.0;

/**
 * @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: @openzeppelin/contracts/token/ERC20/IERC20.sol



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

pragma solidity ^0.8.0;

/**
 * @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: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/draft-IERC20Permit.sol";
import "../../../utils/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: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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 functionCallWithValue(target, data, 0, "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");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or 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 {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // 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: @openzeppelin/contracts/utils/Context.sol



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

pragma solidity ^0.8.0;

/**
 * @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: @openzeppelin/contracts/utils/cryptography/MerkleProof.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/MerkleProof.sol)

pragma solidity ^0.8.0;

/**
 * @dev These functions deal with verification of Merkle Tree proofs.
 *
 * The tree and the proofs can be generated using our
 * https://github.com/OpenZeppelin/merkle-tree[JavaScript library].
 * You will find a quickstart guide in the readme.
 *
 * WARNING: You should avoid using leaf values that are 64 bytes long prior to
 * hashing, or use a hash function other than keccak256 for hashing leaves.
 * This is because the concatenation of a sorted pair of internal nodes in
 * the merkle tree could be reinterpreted as a leaf value.
 * OpenZeppelin's JavaScript library generates merkle trees that are safe
 * against this attack out of the box.
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(
        bytes32[] memory proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProof(proof, leaf) == root;
    }

    /**
     * @dev Calldata version of {verify}
     *
     * _Available since v4.7._
     */
    function verifyCalldata(
        bytes32[] calldata proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProofCalldata(proof, leaf) == root;
    }

    /**
     * @dev Returns the rebuilt hash obtained by traversing a Merkle tree up
     * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
     * hash matches the root of the tree. When processing the proof, the pairs
     * of leafs & pre-images are assumed to be sorted.
     *
     * _Available since v4.4._
     */
    function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            computedHash = _hashPair(computedHash, proof[i]);
        }
        return computedHash;
    }

    /**
     * @dev Calldata version of {processProof}
     *
     * _Available since v4.7._
     */
    function processProofCalldata(bytes32[] calldata proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            computedHash = _hashPair(computedHash, proof[i]);
        }
        return computedHash;
    }

    /**
     * @dev Returns true if the `leaves` can be simultaneously proven to be a part of a merkle tree defined by
     * `root`, according to `proof` and `proofFlags` as described in {processMultiProof}.
     *
     * CAUTION: Not all merkle trees admit multiproofs. See {processMultiProof} for details.
     *
     * _Available since v4.7._
     */
    function multiProofVerify(
        bytes32[] memory proof,
        bool[] memory proofFlags,
        bytes32 root,
        bytes32[] memory leaves
    ) internal pure returns (bool) {
        return processMultiProof(proof, proofFlags, leaves) == root;
    }

    /**
     * @dev Calldata version of {multiProofVerify}
     *
     * CAUTION: Not all merkle trees admit multiproofs. See {processMultiProof} for details.
     *
     * _Available since v4.7._
     */
    function multiProofVerifyCalldata(
        bytes32[] calldata proof,
        bool[] calldata proofFlags,
        bytes32 root,
        bytes32[] memory leaves
    ) internal pure returns (bool) {
        return processMultiProofCalldata(proof, proofFlags, leaves) == root;
    }

    /**
     * @dev Returns the root of a tree reconstructed from `leaves` and sibling nodes in `proof`. The reconstruction
     * proceeds by incrementally reconstructing all inner nodes by combining a leaf/inner node with either another
     * leaf/inner node or a proof sibling node, depending on whether each `proofFlags` item is true or false
     * respectively.
     *
     * CAUTION: Not all merkle trees admit multiproofs. To use multiproofs, it is sufficient to ensure that: 1) the tree
     * is complete (but not necessarily perfect), 2) the leaves to be proven are in the opposite order they are in the
     * tree (i.e., as seen from right to left starting at the deepest layer and continuing at the next layer).
     *
     * _Available since v4.7._
     */
    function processMultiProof(
        bytes32[] memory proof,
        bool[] memory proofFlags,
        bytes32[] memory leaves
    ) internal pure returns (bytes32 merkleRoot) {
        // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
        // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            return hashes[totalHashes - 1];
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    /**
     * @dev Calldata version of {processMultiProof}.
     *
     * CAUTION: Not all merkle trees admit multiproofs. See {processMultiProof} for details.
     *
     * _Available since v4.7._
     */
    function processMultiProofCalldata(
        bytes32[] calldata proof,
        bool[] calldata proofFlags,
        bytes32[] memory leaves
    ) internal pure returns (bytes32 merkleRoot) {
        // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
        // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            return hashes[totalHashes - 1];
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    function _hashPair(bytes32 a, bytes32 b) private pure returns (bytes32) {
        return a < b ? _efficientHash(a, b) : _efficientHash(b, a);
    }

    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}

// File: contracts/Parapad.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

import "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract Parapad is Ownable {
    using SafeERC20 for IERC20;

    address public usdtAddress;
    address public paradoxAddress;

    IERC20 internal para;
    IERC20 internal usdt;

    mapping(address => bool) public _claimed;

    uint256 internal constant PARADOX_DECIMALS = 10 ** 18;
    uint256 internal constant USDT_DECIMALS = 10 ** 6;

    uint256 internal constant EXCHANGE_RATE = 3;
    uint256 internal constant EXCHANGE_RATE_DENOMINATOR = 100;

    uint256 internal constant MONTH = 4 weeks;

    /** MAXIMUM OF $1000 per person */
    uint256 internal constant MAX_AMOUNT = 1000 * USDT_DECIMALS;

    mapping(address => Lock) public locks;

    struct Lock {
        uint256 total;
        uint256 paid;
        uint256 debt;
        uint256 startTime;
    }

    constructor(address _usdt, address _paradox) {
        usdtAddress = _usdt;
        usdt = IERC20(_usdt);

        paradoxAddress = _paradox;
        para = IERC20(_paradox);
    }

    function getClaimed(address _user) external view returns (bool) {
        return _claimed[_user];
    }

    function buyParadox(uint256 amount) external {
        require(!_claimed[msg.sender], "Limit reached");
        require(amount <= MAX_AMOUNT, "Wrong amount");
        // get exchange rate to para
        uint256 rate = (amount * EXCHANGE_RATE_DENOMINATOR * PARADOX_DECIMALS) /
            (USDT_DECIMALS * EXCHANGE_RATE);
        require(rate <= para.balanceOf(address(this)), "Low balance");
        // give user 20% now
        uint256 rateNow = (rate * 20) / 100;
        uint256 vestingRate = rate - rateNow;

        if (locks[msg.sender].total == 0) {
            // new claim
            locks[msg.sender] = Lock({
                total: vestingRate,
                paid: amount,
                debt: 0,
                startTime: block.timestamp
            });

            if (amount == MAX_AMOUNT) _claimed[msg.sender] = true;
        } else {
            // at this point, the user still has some pending amount they can claim
            require(amount + locks[msg.sender].paid <= MAX_AMOUNT, "Too Much");

            locks[msg.sender].total += vestingRate;
            if (amount + locks[msg.sender].paid == MAX_AMOUNT)
                _claimed[msg.sender] = true;
            locks[msg.sender].paid += amount;
        }

        usdt.safeTransferFrom(msg.sender, address(this), amount);
        para.safeTransfer(msg.sender, rateNow);
    }

    // New Function
    function pendingVestedParadox(
        address _user
    ) external view returns (uint256) {
        Lock memory userLock = locks[_user];

        uint256 monthsPassed = (block.timestamp - userLock.startTime) / 4 weeks;
        /** @notice 5% released each MONTH after 2 MONTHs */
        uint256 monthlyRelease = (userLock.total * 5) / 100;
        uint256 release;
        for (uint256 i = 0; i < monthsPassed; i++) {
            if (i >= 2) {
                if (release >= userLock.total) {
                    release = userLock.total;
                    break;
                }
                release += monthlyRelease;
            }
        }

        return release - userLock.debt;
    }

    // New Function
    function claimVestedParadox() external {
        Lock storage userLock = locks[msg.sender];
        require(userLock.total > userLock.debt, "Vesting Complete");

        uint256 monthsPassed = (block.timestamp - userLock.startTime) / 4 weeks;
        /** @notice 5% released each MONTH after 2 MONTHs */
        uint256 monthlyRelease = (userLock.total * 5) / 100;

        uint256 release;
        for (uint256 i = 0; i < monthsPassed; i++) {
            if (i >= 2) {
                if (release >= userLock.total) {
                    release = userLock.total;
                    break;
                }
                release += monthlyRelease;
            }
        }

        uint256 reward = release - userLock.debt;
        userLock.debt += reward;
        para.transfer(msg.sender, reward);
    }

    function withdrawTether(address _destination) external onlyOwner {
        usdt.safeTransfer(_destination, usdt.balanceOf(address(this)));
    }

    /** @notice EMERGENCY FUNCTIONS */
    function updateClaimed(address _user) external onlyOwner {
        _claimed[_user] = !_claimed[_user];
    }

    function updateUserLock(
        address _user,
        uint256 _total,
        uint256 _paid,
        uint256 _startTime
    ) external onlyOwner {
        Lock storage lock = locks[_user];
        lock.total = _total;
        lock.paid = _paid;
        lock.startTime = _startTime;
    }

    function withdrawETH() external onlyOwner {
        address payable to = payable(msg.sender);
        to.transfer(address(this).balance);
    }

    function withdrawParadox() external onlyOwner {
        para.safeTransfer(msg.sender, para.balanceOf(address(this)));
    }
}

// File: contracts/ParapadV2.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "./Parapad.sol";

contract ParapadV2 is Ownable {
    using SafeERC20 for IERC20;

    address public usdtAddress;
    address public paradoxAddress;

    IERC20 internal para;
    IERC20 internal usdt;

    Parapad public parapadV1;

    mapping(address => bool) public _claimed;

    uint256 internal constant PARADOX_DECIMALS = 10 ** 18;
    uint256 internal constant USDT_DECIMALS = 10 ** 6;

    uint256 internal constant EXCHANGE_RATE = 3;
    uint256 internal constant EXCHANGE_RATE_DENOMINATOR = 100;

    uint256 internal constant MONTH = 4 weeks;

    /** MAXIMUM OF $1000 per person */
    uint256 internal constant MAX_AMOUNT = 1000 * USDT_DECIMALS;

    mapping(address => Lock) public locks;
    
    mapping(address => bool)public islockedOnV2;

    struct Lock {
        uint256 total;
        uint256 paid;
        uint256 debt;
        uint256 startTime;
    }

    constructor(address _usdt, address _paradox, address _parapadV1) {
        usdtAddress = _usdt;
        usdt = IERC20(_usdt);

        paradoxAddress = _paradox;
        para = IERC20(_paradox);
        parapadV1 = Parapad(_parapadV1);
    }

    function buyParadox(uint256 amount) external {
        
        // Check if user already claimed on ParapadV1 or ParapadV2
        bool claimed = islockedOnV2[msg.sender] ? _claimed[msg.sender] : parapadV1._claimed(msg.sender);
        
        require(!claimed, "Limit reached");

        require(amount <= MAX_AMOUNT, "Wrong amount");
        // get exchange rate to para
        uint256 rate = (amount * EXCHANGE_RATE_DENOMINATOR * PARADOX_DECIMALS) /
            (USDT_DECIMALS * EXCHANGE_RATE);

        require(rate <= para.balanceOf(address(this)), "Low balance");
        // give user 20% now
        uint256 rateNow = (rate * 20) / 100;
        
        uint256 vestingRate = rate - rateNow;

        Lock memory userLock;
        
        // Getting userLock from ParapadV2 or ParapadV1 if user triggers function for the first time
       if(islockedOnV2[msg.sender]){
              userLock = locks[msg.sender];
        }else{
            (uint256 total, uint256 paid, uint256 debt, uint256 startTime) = parapadV1.locks(msg.sender);
              userLock.total = total;
              userLock.paid = paid;
              userLock.startTime = startTime;
              userLock.debt = debt;
        }

        if (userLock.total == 0) {
            // new claim
            locks[msg.sender] = Lock({
                total: vestingRate,
                paid: amount,
                debt: 0,
                startTime: block.timestamp
            });

            if (amount == MAX_AMOUNT) _claimed[msg.sender] = true;

        } else {
            // at this point, the user still has some pending amount they can claim
            require(amount +  userLock.paid <= MAX_AMOUNT, "Too Much");

            userLock.total += vestingRate;

            if (amount + userLock.paid == MAX_AMOUNT) _claimed[msg.sender] = true;

            userLock.paid += amount;
        }
        
        // Save userLock info to the storage
        locks[msg.sender] = userLock;

        // Update mapping to identify where to fetch info about user lock
        if(!islockedOnV2[msg.sender]){
          islockedOnV2[msg.sender] = true;
        }

        usdt.safeTransferFrom(msg.sender, address(this), amount);
        para.safeTransfer(msg.sender, rateNow);
    }

    function pendingVestedParadox(
        address _user
    ) external view returns (uint256) {
          Lock memory userLock;

         if(islockedOnV2[_user]){
              userLock = locks[_user];
         }else{
            (uint256 total, uint256 paid, uint256 debt, uint256 startTime) = parapadV1.locks(msg.sender);
              userLock.total = total;
              userLock.paid = paid;
              userLock.startTime = startTime;
              userLock.debt = debt;
         }

        uint256 monthsPassed = (block.timestamp - userLock.startTime) / 4 weeks;
        /** @notice 5% released each MONTH after 2 MONTHs */

        uint256 monthlyRelease =  (userLock.total * 100 / 80) * 5 / 100;

        uint256 release;
        for (uint256 i = 0; i < monthsPassed; i++) {
            if (i >= 2) {
                if (release >= userLock.total) {
                    release = userLock.total;
                    break;
                }
                release += monthlyRelease;
            }
        }

        return release - userLock.debt;
    }

    function claimVestedParadox() external {
         Lock memory userLock;

         if(islockedOnV2[msg.sender]){
              userLock = locks[msg.sender];
         }else{
            (uint256 total, uint256 paid, uint256 debt, uint256 startTime) = parapadV1.locks(msg.sender);
              userLock.total = total;
              userLock.paid = paid;
              userLock.startTime = startTime;
              userLock.debt = debt;
         }

        require(userLock.total > userLock.debt, "Vesting Complete");

        uint256 monthsPassed = (block.timestamp - userLock.startTime) / 4 weeks;
        
        // All lock including 20% which user already got buyingParadox
        
        /** @notice 5% released each MONTH after 2 MONTHs */
        uint256 monthlyRelease =  (userLock.total * 100 / 80) * 5 / 100;

        uint256 release;
        for (uint256 i = 0; i < monthsPassed; i++) {
            if (i >= 2) {
                if (release >= userLock.total) {
                    release = userLock.total;
                    break;
                }
                release += monthlyRelease;
            }
        }
        uint256 reward = release - userLock.debt;
        userLock.debt += reward;
        
        // Save userLock info to the storage
        locks[msg.sender] = userLock;      
        
        // Update mapping to identify where to fetch info about user lock
        if(!islockedOnV2[msg.sender]){
          islockedOnV2[msg.sender] = true;
        }

        para.transfer(msg.sender, reward);
    }

    function getUserNextClaimTimestamp(address _user) external view returns(uint256){
         Lock memory userLock;

         if(islockedOnV2[_user]){
              userLock = locks[_user];
         }else{
            (uint256 total, uint256 paid, uint256 debt, uint256 startTime) = parapadV1.locks(msg.sender);
              userLock.total = total;
              userLock.paid = paid;
              userLock.startTime = startTime;
              userLock.debt = debt;
         }
        
        uint256 monthsPassed = (block.timestamp - userLock.startTime) / 4 weeks;
        
        uint256 nextClaimTimestamp = monthsPassed + MONTH;

         return nextClaimTimestamp - block.timestamp;
    }

     function getUserClaimed(address _user) external view returns(uint256){
         Lock memory userLock;

         if(islockedOnV2[_user]){
              userLock = locks[_user];
         }else{
            (uint256 total, uint256 paid, uint256 debt, uint256 startTime) = parapadV1.locks(msg.sender);
              userLock.total = total;
              userLock.paid = paid;
              userLock.startTime = startTime;
              userLock.debt = debt;
         }

         return userLock.debt;
    }

     function getUserLeftToClaim(address _user) external view returns(uint256){
         Lock memory userLock;

         if(islockedOnV2[_user]){
              userLock = locks[_user];
         }else{
            (uint256 total, uint256 paid, uint256 debt, uint256 startTime) = parapadV1.locks(msg.sender);
              userLock.total = total;
              userLock.paid = paid;
              userLock.startTime = startTime;
              userLock.debt = debt;
         }

         return userLock.total - userLock.debt;
    }

    function withdrawTether(address _destination) external onlyOwner {
        usdt.safeTransfer(_destination, usdt.balanceOf(address(this)));
    }

    function updateParadoxV1(address _paradoxV1) external onlyOwner {
        parapadV1 = Parapad(_paradoxV1);
    }

     function updateParadoxAddress(address _paradox) external onlyOwner {
        para = IERC20(_paradox);
    }

     function updateUsdtAddress(address _usdt) external onlyOwner {
        usdt = IERC20(_usdt);
    }

    /** @notice EMERGENCY FUNCTIONS */
    function updateClaimed(address _user) external onlyOwner {
        _claimed[_user] = !_claimed[_user];
    }

    function updateUserLock(
        address _user,
        uint256 _total,
        uint256 _paid,
        uint256 _startTime
    ) external onlyOwner {
        Lock storage lock = locks[_user];
        lock.total = _total;
        lock.paid = _paid;
        lock.startTime = _startTime;
    }

    function withdrawETH() external onlyOwner {
        address payable to = payable(msg.sender);
        to.transfer(address(this).balance);
    }

    function withdrawParadox() external onlyOwner {
        para.safeTransfer(msg.sender, para.balanceOf(address(this)));
    }
}