using System;

​

​

public class Program

{

    public class Abacus

    {

        public int SumTwo(int a, int b)

        {

            return a+b;

        }

        public int SubtractTwo(int a, int b)

        {

            return a-b;

        }

    }

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}