using System;

namespace Demoabstraction {

// abstract class

abstract class Shape {

    // abstract method

    public abstract int area();

}

// square class inheriting

// the Shape class

 class Square : Shape {

    // private data member

    private int side;

    // method of  square class

    public Square(int x = 0)

    {

        side = x;

    }

    // overriding of the abstract method of Shape

    // class using the override keyword

    public override int area()

    {

        Console.Write("Area of Square: ");

        return (side * side);

    }

}

    class ractengal : Shape {

    // private data member

    private int side;

    // method of  square class

    public ractengal (int x = 0)

    {

        side = x;

    }

    // overriding of the abstract method of Shape

    // class using the override keyword

    public override int area()

    {

        Console.Write("Area of Ractengale: ");

        return (side * (side/2));

    }

}

// Driver Class

public class GFG {

    // Main Method

    public static void Main(string[] args)

    {

        // creating reference of Shape class

        // which refer to Square class instance

        Shape sh = new Square(2);

        // calling the method

        double result = sh.area();

        Console.Write("{0}", result);

           Shape shra = new ractengal(8);

         double ractengalresult = shra.area();

        Console.Write("{0}", ractengalresult);

    }

}

}