Vault.sol

pragma solidity 0.8.7;

contract Vault {
    mapping(address => uint256) public accountBalance;

    function withdraw(uint256 amount) public {
        uint256 currentBalance = accountBalance[msg.sender];
        require(amount <= currentBalance, "Account balance is not enough");

        accountBalance[msg.sender] -= amount;
        payable(msg.sender).transfer(amount);
    }

    function deposit() public payable {
        accountBalance[msg.sender] += msg.value;
    }

    receive() external payable {
        accountBalance[msg.sender] += msg.value;
    }

    fallback() external payable {
        accountBalance[msg.sender] += msg.value;
    }
}