using System;

using System.Collections.Generic;

public class Program

{

    public class Shape

    {

        public int X { get; private set; }

        public int Y { get; private set; }

        public int Height { get; set; }

        public int Width { get; set; }  

        //virtual method 

        public virtual void Draw()

        {

            Console.WriteLine("base class draw tasks"); 

        }

    }

    public class Circle : Shape

    {

        public override void Draw()

        {

            //draw circle

            Console.WriteLine("Draw Circle");

            base.Draw();

        }

    }

    public class Rectangle : Shape

    {

        public override void Draw()

        {

        // Code to draw a rectangle...

        Console.WriteLine("Drawing a rectangle");

        base.Draw();

        }

    }

    public class Triangle : Shape

    {

        public override void Draw()

        {

        // Code to draw a triangle...

        Console.WriteLine("Drawing a triangle");

        base.Draw();

        }

    }

    public static void Main()

    {

        List<Shape> shapes = new List<Shape>();

        shapes.Add(new Circle());

        shapes.Add(new Rectangle());

        shapes.Add(new Triangle());

        foreach (Shape s in shapes)

        {

            s.Draw();

        }

    }

}