using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CalCulator
{
    class Program
    {
        public double calculate(double x1, double x2, string operation)
        {
        double result = 0;
        switch(operation)
                {
                case "-":
                   result =  x1 - x2;
                    break;
                case "+":
                     result = x1 + x2;
                    break;
                case "*":
                    result = x1* x2;
                    break;
                case "/":
                   if(x2 == 0)
                    {
                        Console.WriteLine("ты неверный!!!!!");
                        break;
                    }
                result = x1 / x2;
                    break;
                case "%":
                     result = x1 % x2;
                    break;
        }
        return result;
            }


static void Main(string[] args)
        {
            Console.WriteLine("let's start");
            string expression = Console.ReadLine();

            string[] split = expression.Split(new char[] { '+', '-', '/', '*', '%' });

            int operationIndex = Convert.ToInt32(split[0].Length);
            double x1 = Convert.ToDouble(split[0]);
            double x2 = Convert.ToDouble(split[1]);
            String operation1 = expression.Substring(operationIndex, 1);

            double result = calculate(x1, x2, operation1);


              Console.WriteLine(result);

                Console.ReadKey();

        }
    }
}