using System;
public class Program
{
    static void Main()
    {
        string s = Console.ReadLine();
        int sum = 0;
        for (int i = 0; i < s.Length; i++)
        {
            if (char.IsDigit(s, i))
            {
                sum += int.Parse(s[i].ToString());
            }
        }
        Console.WriteLine(sum);
    }
}