using System;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

public class Program

{

    public static void Main(string[]args)

    {

  do {

  string str = Console.ReadLine();

  if (str == "exit")

    break;

double x = Convert.ToDouble(str);

 string o= Console.ReadLine();

  char op= Convert.ToChar(o);

​

  double y = Convert.ToDouble(Console.ReadLine());

  switch(op){

  case '+':

  double sum = x + y;

  Console.WriteLine(" = {0}", sum);

  x=sum;

  break;

  case '-':

  double dif = x - y;

  Console.WriteLine(" = {0}", dif);

  x=dif;

  break;

  case '*':

  double prod = x * y;

  Console.WriteLine(" = {0}", prod);

  x=prod;

  break;

  case '/':

  double quo = x / y;

  Console.WriteLine(" = {0}", quo);

  x=quo;

  break;

    }

}

while (true);

  }

}

​