using System;

​

public class Program

{

  abstract class Shape {

    public abstract void Draw();

  }

​

  class Circle : Shape {

    public override void Draw() {

      // draw a circle!

      Console.WriteLine("Imagine a circle is drawn");

    }

  }

​

  class Rectangle : Shape {

    public override void Draw() {

      // draw a rectangle!

      Console.WriteLine("Imagine a rectangle is drawn");

    }

  }

​

  public static void Main() {

    Shape c = new Circle();

    c.Draw();

    // Imagine a circle is drawn

  }

}