using System;

public class Program

{

    class A{

    }

    class B : A{

    }

    class C{

    }

    public static void Main()

    {

        object b = new B();

        object c = new C();

        A a1 = b as A;

        Console.WriteLine("1" + a1);

        A a2 = (A)b;

        Console.WriteLine("2" + a2);

        A a3 = c as A;

        Console.WriteLine("3" + a3);

        A a4 = (A)c;

        Console.WriteLine("4" + a4);

    }

}