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

class Program
{
    static string InputPattern = "Input4";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("12");
            //21
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("21");
            //21
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("1122");
            //2211
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        string NStr = InputList[0];

        char[] StrArr = NStr.ToCharArray();
        Array.Sort(StrArr, (A, B) => B.CompareTo(A));

        var sb = new System.Text.StringBuilder();
        Array.ForEach(StrArr, X => sb.Append(X));
        Console.WriteLine(sb.ToString());
    }
}