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

namespace yukicoder
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            int t, ans;
            ans = 0;
            for(int i = 0;i< s.Length; i++)
            {
                if (int.TryParse(s[i].ToString(), out t))
                {
                    ans += t;
                }
            }

            Console.WriteLine("{0}", ans);
            //Console.ReadLine();

        }
    }
}