using System;

public class Program

{

    public static void Main()

    {

        var kotak = new Persegi(5);

        kotak.Name("Persegi");

        Console.WriteLine(kotak.Process());

        var kotak2 = new PersegiPanjang(5,10);

        kotak2.Name("Persegi Panjang");

        Console.WriteLine(kotak2.Process());

        var kotak3 = new PersegiPanjang();

        kotak3.Name("PersegiPanjang2");

        Console.WriteLine(kotak3.Process());

    }

}

​

public class Persegi : BangunRuang2D

{

    public double sisi {get;set;}

    public Persegi(double s){

        sisi = s;

    }

    public override double Process(){

        return sisi*sisi;

    }

}

​

public class PersegiPanjang : BangunRuang2D

{

    public double panjang {get;set;}

    public double lebar {get;set;}

    //constructor

    public PersegiPanjang(){

        panjang = 10;

        lebar = 7;

    }

    //constructor overloading

    public PersegiPanjang(double p, double l){

        panjang = p;

        lebar = l;

    }

    public override double Process(){

        return panjang*lebar;

    }

}

​

public abstract class BangunRuang2D

{

    public abstract double Process();

    public void Name(string val){

        Console.Write("Luas Bangun Ruang "+ val + " : ");

    }

}