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

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            if (s.Length == 1)
            {
                if ('0' != s[0]) Console.WriteLine(13);
                else Console.WriteLine(1);
            }
            else
           if (s.Length == 2)
            {
                if ('0' != s[0]) Console.WriteLine(13);
                else
                    if ('0' != s[1]) Console.WriteLine(13);
                else Console.WriteLine(1);
            }
            else
            if (s.Length == 3)
            {
                if ('0'!=s[2]) Console.WriteLine(13);
                else
                    if (s[0] != s[1]) Console.WriteLine(13);
                else Console.WriteLine(1);
            }
            else
            if (s.Length == 4)
            {
                if (s[0] != s[3]) Console.WriteLine(13);
                else
                    if (s[1] != s[2]) Console.WriteLine(13);
                else Console.WriteLine(1);
            }
        }

    }
}