using System;
using System.Linq;

class Program
{
    static void Main()
    {
        var inp = Console.ReadLine();
        int ans = 0;
        foreach (var c in inp)
        {
            int i = (int)Char.GetNumericValue(c);
            if(i >= 0 && i <= 9)
            {
                ans += i;
            }
        }
        Console.WriteLine(ans);
    }
}