using System;

namespace AtCoder
{
    class Program
    {
        static void Main()
        {
            string line = Console.ReadLine();
            int sum = 0;
            foreach (var c in line)
            {
                if (int.TryParse(c.ToString(), out int num))
                {
                    sum += num;
                }
            }
            Console.WriteLine(sum);
        }
    }
}