using System.Numerics;

public class Program
{
    public static void Main()
    {
        BigInteger num = BigInteger.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        //string str = Console.ReadLine() ?? string.Empty;
        int a = num.ToString().Length;

        int c = 0;
        for(int i = 0; i < a; i++)
        {
            if (num.ToString()[i] == '0')
            {
                c++;
            }
        }
        Console.WriteLine(a - 1-c);

    }
}