using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using static System.Math;

namespace SortItems
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = Console.ReadLine();
            var ans = n.ToCharArray();
            Array.Sort(ans);
            Array.Reverse(ans);

            Console.WriteLine(ans);

        }
    }
}