using System;

​

namespace Rextester

{

    public class Program

    {

        public static void Main(string[] args)

        {

            Activate();

        }

        static void yesss()

        {

            Activate();

        }

        static void Activate()

        {

            Console.WriteLine("Multiplication, division, addition or subtraction?");

            string thing = Console.ReadLine();

            float firstNum;

            float secondNum;

            float result;

            if (thing == "Multiplication" || thing == "multiplication" || thing == "Multiplikation" || thing == "multiplikation")

            {

                Console.WriteLine("first number");

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

                Console.WriteLine("second number");

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

                result = firstNum * secondNum;

                Console.WriteLine("Result is " + result);

            }

            if (thing == "Division" || thing == "division")

            {

                Console.WriteLine("first number");

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

                Console.WriteLine("second number");

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

                result = firstNum / secondNum;

                Console.WriteLine("Result is " + result);

            }

            if (thing == "Addition" || thing == "addition")

            {

                Console.WriteLine("first number");

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

                Console.WriteLine("second number");

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

                result = firstNum + secondNum;

                Console.WriteLine("Result is " + result);

            }

            if (thing == "subtraktion" || thing == "Subtraktion")

            {

                Console.WriteLine("first number");

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

                Console.WriteLine("second number");

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

                result = firstNum + secondNum;

                Console.WriteLine("Result is " + result);

            }

            Console.WriteLine("again?");

            string yes = Console.ReadLine();

            if (yes == "yes" || yes == "Yes")

            {

                yesss();

            } else if (yes == "no" || yes == "No") 

            {

                Console.WriteLine("Ok, bye");

            }

        }

    }

}