pragma solidity ^0.4.1;

contract C1 {

    uint x;

    constructor() public {
        x = 10;
    }

    function setX(uint _x) public returns(bool) {
        x = _x;
        return true;
    }

    function getX() public view returns(uint) {
        return x;
    }
}

contract C2 {

    function f2(address addrC1) public view returns(uint) {
        C1 c1 = C1(addrC1);
        return c1.getX();
    }

}