class Program
{
    static void Main(string[] args)
    {
        string num = Console.ReadLine()!;

        if (!num.Contains("0"))
        {
            Console.WriteLine(num.Length - 1);
        }
        else
        {
            int count = 0;
            foreach (char c in num)
            {
                if (c == '0')
                {
                    count++;
                }
            }

            Console.WriteLine(num.Length - 1 -  count);
        }
    }
}