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

namespace YukiCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Console.ReadLine().Count(a => a == '0');

            Console.WriteLine(n > 8 ? n - 8 : 8 - n);
            Console.ReadLine();
        }
    }
}