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

namespace pj1
{
    class Program
    {
        static void Main(string[] args)
        {
            string line = Console.ReadLine();

            int sum = 0;

            for (int i = 0; i < line.Length; i++)
            {
                int number = int.Parse(line.Substring(i, 1));
                sum += number;
            }

            Console.WriteLine(sum);           
        } 
    }
}