using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace algo {
    class Program
    {
        static void Main(string[] args)
        {
            string N = Console.ReadLine(); //Console.ReadLine().Split(' ');
            int ans = 0;
            int copy;
            for(int i = 0; i < N.Length; i++)
            {
                if (int.TryParse(N[i].ToString(), out copy))
                {
                    ans += copy;
                }
            }
            Console.WriteLine(ans);
        }
    }
}