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

namespace y1168
{
    class Program
    {
        static void Main(string[] args)
        {
            int num = int.Parse(Console.ReadLine());
            int ans = num % 9;
            if(ans == 0)
            {
                ans = 9;
            }
            Console.WriteLine(ans);
        }
    }
}