using System;

public class Program

{

    public static void Main()

    {

         {

            double a, b;

             string var1;

​

            Console.WriteLine("What is variable a? ");

          a = Convert.ToInt32(Console.ReadLine());

​

            Console.WriteLine("What is variable b? ");

          b = Convert.ToInt32(Console.ReadLine());

​

​

            Console.WriteLine("If plus type add, for minus type subtract");

            var1 = Console.ReadLine();

​

            if (var1 == "add")

​

            {

​

                Console.WriteLine(a + b);

                Console.ReadLine();

​

            }

​

​

            else

​

            {

​

                Console.WriteLine(a - b);

                Console.ReadLine();

​

            }

​

        }

    }

}