using System;

public class Program {

    public static void Main() {

        Y parent = new Y();

        X child = new X();

        Console.WriteLine("Parent: " + parent.varOne);

        Console.WriteLine("Child: " + child.varOne);

        Console.WriteLine("Test: " + child.a().b());

    }

}

​

public class Y {

    public string varOne = "1";

    public Y a() { return this; }

}

​

public class X : Y {

    public string varTwo = "x";

    public X() { this.varOne = "2"; }

    public string b(){ return "Sono X";}

}