using System;

public class Program

{

    public abstract class shape{

     public abstract void getarea();

    }

    public class rectangle:shape

    {

    public int ht{get;set;}

    public int wdt{get;set;}

     public override void getarea()

     {

     //callulate rect area

     }

    }

    public class square:shape

    {

    public int len{get;set;}

    public  override void getarea(){

    ////callulate square area

    }

    }

    public class circle: shape

    {

    public int radius{get;set;}

    public  override void getarea(){

    ////callulate circle area

    }

    }

    // if new circle inroduced i need to change the caclculatearea class

    public class calculatearea{

    public void getarea(shape[] shape)

    {

    //based on shape call the area ethod

    }

    }

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}