using System;

public class Program

{

    public abstract class Animal

    {

        public string MakeNoise()

        {

            return "(silence)";

        }

    }

    public class Dog : Animal

    {

        public string MakeNoise()

        {

            return "woof";

        }

    }

    public class Cat : Animal

    {

        public string MakeNoise()

        {

            return "meow";

        }

    }

    public static void Main()

    {

        Dog dog = new Dog();

        Console.WriteLine("The sound this dog makes: " + dog.MakeNoise());

        //Animal[] animals = new Animal[] { new Dog(), new Cat(), new Dog() };

        //foreach(Animal animal in animals)

        //{

        //  Console.WriteLine("The sound this animal makes: " + animal.MakeNoise());

        //}

    }

}