using System;
using System.Collections.Generic;
using System.Linq;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            int[] a = new int[10];
            for (int i = 0; i < s.Length; i++)
            {
                a[int.Parse(s[i].ToString())]++;
            }
            for (int i = 9; i >= 0; i--)
            {
                for (int j = 0; j < a[i]; j++) Console.Write(i);
            }
            Console.WriteLine();
        }
    }
}