using System;
using System.Text;

namespace y
{
    class Program
    {
        static void Main(string[] args)
        {
            string n = Console.ReadLine();
            int[] c = new int[10];

            foreach (var i in n)
            {
                switch (i)
                {
                    case '0':
                        c[0]++;
                        break;
                    case '1':
                        c[1]++;
                        break;
                    case '2':
                        c[2]++;
                        break;
                    case '3':
                        c[3]++;
                        break;
                    case '4':
                        c[4]++;
                        break;
                    case '5':
                        c[5]++;
                        break;
                    case '6':
                        c[6]++;
                        break;
                    case '7':
                        c[7]++;
                        break;
                    case '8':
                        c[8]++;
                        break;
                    case '9':
                        c[9]++;
                        break;
                }
            }

            var sb = new StringBuilder();
            for (int i = 9; i >= 0; i--)
            {
                for (int j = 0; j < c[i]; j++)
                {
                    sb.Append(i.ToString());
                }
            }

            Console.WriteLine(sb.ToString());
        }
    }
}