using System;

public class Program

{

    interface Animal {

         void P();

    }

    class Dog : Animal {

        public void P() { Console.WriteLine("D"); }

    }

    class Cat : Animal {

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

    }

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Dog[] dogArray = new Dog[5];

Animal[] animalArray = dogArray;

animalArray[0] = new Cat();

        Console.WriteLine("Hello World2");

dogArray[0].P();

    }

}