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BankAccount.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.8.0;

contract BounceBack {

    address payable internal owner;

    constructor() {
        owner = msg.sender;
    }
    
    modifier onlyOwner() {
        require(msg.sender == owner, "Owner called this");
        _;
    }

    function payout() external onlyOwner {
        // Withdraw balance
        owner.transfer(address(this).balance);
    }


    receive() external payable {
        // Deposit money
    }
}

YouGet5.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.8.0;

contract YouGet5 {

    address payable internal owner;
    
    modifier onlyOwner() {
        require(msg.sender == owner, "Owner called this");
        _;
    }

    constructor() {
        owner = msg.sender;
    }
    
    function payout() external onlyOwner {
        owner.transfer(address(this).balance);
    }
    
    function destroy() external onlyOwner {
        selfdestruct(owner);
    }
    
    function getSenderBalance() internal view returns (uint256) {
        return msg.sender.balance;
    }
    
    function getContractBalance() internal view returns (uint256) {
        return address(this).balance;
    }
    
    function calculateDeposit() internal view returns (uint256) {
        return (5000000000000000000 - getSenderBalance());
    }
    
    receive() external payable {
        uint256 balance = getSenderBalance();
        if (balance < 5000000000000000000) {
            uint256 deposit = calculateDeposit();
            if (deposit < getContractBalance()) {
                msg.sender.transfer(deposit);
            }
        }
    }
}