pragma solidity >=0.4.0 <0.7.0;

contract AddOne {
    uint public value;

    function increment() public {
        value = value + 1;
    }
}

contract AddTwo {
    uint public value;

    function increment() public {
        value = value + 2;
    }
}

contract Proxy {
    uint public result;
    address logicContract;

    function upgrade(address _newLogicContract) public {
        logicContract = _newLogicContract;
    }

    function () external {
        (bool success, ) = logicContract.delegatecall(msg.data);
        require(success);
    }
}