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

public class yukicoder
{
    public static void Main()
    {
    	List<long> lst = new List<long>();
    	
    	foreach(char c in Console.ReadLine())
    	{
    		lst.Add(long.Parse(c.ToString()));
    	}
    	
    	lst.Sort();
    	lst.Reverse();

    	
    	for(int i = 0; i < lst.Count; i++)
    	{
    		Console.Write(lst[i]);
    	}
    }
}