using System;

​

public class Program

{

    public static void Main()

    {

        // Instantiate a Dog class and set the number of legs

        Dog dog = new Dog();

        dog.NumberOfLegs = 4;

        // Instantiate a Bird class and set the number of legs

        Bird bird = new Bird();

        bird.NumberOfLegs = 2;

        // write out the number of legs of each animal

        Console.WriteLine(dog.NumberOfLegs);

        Console.WriteLine(bird.NumberOfLegs);

    }

}

​

public class Animal

{

    public int NumberOfLegs { get; set; }

}

​

public class Dog : Animal

{

}

​

public class Bird : Animal

{

}