// SPDX-License-Identifier: MIT
pragma solidity 0.8.8;

contract SimpleStorage {

    uint256 favoriteNumber;

    function store(uint256 _favoriteNumber) public {
        favoriteNumber = _favoriteNumber;
    }
    
    function retrieve() public virtual returns (uint256){
        return favoriteNumber;
    }

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./SimpleStorage.sol";

contract ExtraStorage is SimpleStorage {

    function retrieve() public view override returns (uint256){
        return favoriteNumber + 5;
    }

}