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

namespace kkk
{
    class Program
    {


        static void Main(string[] args)
        {
            string line = Console.ReadLine();
            //"12314543"; // -> 23

            //int.Parse 文字列を数値にする
            int sum = 0;
         

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




            Console.WriteLine(sum);





        }
    }
}