using System;

class Program
{
    static void Main(string[] args)
    {
        string S = Console.ReadLine();
        int num = 0, sum = 0;

        for (int i = 0; i <= S.Length-1; i++)
        {
            if (int.TryParse(S.Substring(i,1), out num))
                sum += num;
        }

        Console.WriteLine(sum);
    }
}