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

namespace Array_Search_Workshop
{
    class Program
    {
        static void Main(string[] args)
        {

            List<int> array = new List<int>(Array.ConvertAll(Console.ReadLine().Split(','), int.Parse));
            List<string> result = new List<string>();

            for (int i = 1; i <= array.Count; i++)
            {
                if (!array.Distinct().Contains(i))
                {
                    result.Add(i.ToString());
                }
            }
            Console.WriteLine(string.Join(",",result));


        }
    }
}