using System;

​

public interface I { void Go(); }

​

public class A : I

{

    public void Go() { Console.WriteLine("A.Go()"); }

}

​

public class B : A { }

​

public class C : B, I

{

    public new void Go() { Console.WriteLine("C.Go()"); }

}

​

public class Program

{

    public static void Main()

    {

        B b1 = new B();

        C c1 = new C();

        B b2 = c1;

        b1.Go();

        c1.Go();

        b2.Go();

        ((I)b2).Go();

    }

}