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


    class Program
    {
        static void Main()
        {
        string input;
        int number;
        input = Console.ReadLine();
        if (!int.TryParse(input, out number) || number < 1000 || number > 9999)
        {
            Console.WriteLine("wrong");
        }
        else {
            int digit_1 = number / 1000;
            int digit_2 = (number / 100) % 10;
            int digit_3 = (number % 100) / 10;
            int digit_4 = number % 10;
            int result = (10 * digit_1 + digit_2) - (10 * digit_4 + digit_3) + 1;
            Console.WriteLine(result);
        }
    }
    }