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

namespace jyugyu_b
{
    class Program
    {
        static void Main(string[] args)
        {
            string line = Console.ReadLine();
            //string line = "12314543";


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

            Console.WriteLine(kazu);
             
        }
    }
}