using System.Collections.Generic;
using System.Numerics;
using System.Linq;
using System;

namespace CroockedDIgits
{
    class Program
    {
        static void Main(string[] args)
        {

            List<decimal> n = Console.ReadLine().Split('.').Select(decimal.Parse).ToList();

            string digits = string.Join("", n);

            Int64 number = Math.Abs(Int64.Parse(digits));

            Int64 sum = 0;

            while (number != 0)
            {

                sum += number % 10;

                number /= 10;

                if (sum > 9)
                {
                    sum = sum - 9;
                    continue;
                }
            }

            Console.WriteLine(sum);
        }
    }
}