using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        A obj1 = new A();

        obj1.Foo();

        obj1.Foo2();

        B obj2 = new B();

        obj2.Foo();

        obj2.Foo2();

        A obj3 = new B();

        obj3.Foo();

        obj3.Foo2();

        B obj4 = obj3 as B;

        if(obj4!=null){

            Console.WriteLine("Success");

            ((B)obj4).Foo();    

            ((B)obj4).Foo2();

        }

        else{

            Console.WriteLine("Fail");

        }

    }

}

​

class A{

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

    public void Foo2(){Console.WriteLine("A2");}

    }

class B:A{

    public override void Foo(){Console.WriteLine("B");}

    public new void Foo2(){Console.WriteLine("B2");}

}