using System.Numerics;

public class Program
{
    public static void Main()
    {

        //BigInteger num = BigInteger.Parse(Console.ReadLine() ?? string.Empty);
        //int num = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        string str = Console.ReadLine() ?? string.Empty;

        string h = str;
        string aa = "";
        for(int i = str.Length-1; i >= 0; i--)
        {
            if (char.IsLower(str[i]))
            {
                string f = str[i].ToString();
                h = h.Replace(f,"");
                aa += str[i];
            }
        }
       
        Console.WriteLine(aa+h);
    }

}