using System;

public class Program

{

    public static void Main()

    {

        int x,ab,de,c;

        x=int.Parse(Console.ReadLine());

        ab=x/1000;

        de=x%100;

        c=x%1000/100;

        if(x>9999 && x<100000 && c==0)

        Console.WriteLine(ab+de);

            else

            { if(x>9999 && x<100000 && c==1)

                Console.WriteLine(ab-de);

             else

                 if(x>9999 && x<100000 && c==2)

                     Console.WriteLine(ab*de);

             else

                 if(x>9999 && x<100000 && c==3)

                     Console.WriteLine(ab/de);

             else

                 if(x<9999 && x>100000)

                     Console.WriteLine("invalid number");

             else

                 if(c!=0 && c!=1 && c!=2 && c!=3)

                     Console.WriteLine("invalidd number"); 

            }

    }

}