Storage.sol

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8;

import '@openzeppelin/contracts/access/Ownable.sol';

contract Storage is Ownable {

    uint256 number;

    constructor() Ownable() {}
    
    function store(uint256 num) public onlyOwner {
        number = num;
    }

    function retrieve() public view returns (uint256){
        return number;
    }
}