using System;

class Program
{
    static void Main()
    {
        string n = Console.ReadLine();

        char[] c = new char[n.Length];
        for (int i = 0; i < n.Length; i++)
        {
            c[i] = n[i];
        }

        Array.Sort(c);
        Array.Reverse(c);

        for (int i = 0; i < n.Length; i++)
        {
            Console.Write(c[i]);
        }

        Console.WriteLine();
    }
}