HelloWorld.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.16;
contract HelloWorld {
    uint256 counter = 5;

    function add() public {  //increases counter by 1
        counter++;
    }

    function subtract() public { //decreases counter by 1
        counter--;
    }

    function getCounter() public view returns (uint256) {
        return counter;
    }

}