using System;

​

public class calc{

    public void add(int num1,int num2){

        Console.WriteLine("product is  "+(num1+num2));

        Console.WriteLine("\n");

    }

}

​

public class calc2 : calc{

    public void add(string n1,string n2){

        Console.WriteLine("product is  "+(n1+n2));

    }

}

​

public class Program

{

    public static void Main()

    {

        calc2 co = new calc2();

        co.add(30,10);

        co.add("yash","raj");

    }

}