using System;

class Program
{
    static void Main(string[] args)
    {
        string input = Console.ReadLine();
        string result = GetAlternatingString(input);
        Console.WriteLine(result);
    }

    static void Shuffle(char[] array)
    {
        Random rand = new Random();
        for (int i = array.Length - 1; i > 0; i--)
        {
            int j = rand.Next(i + 1);
            char temp = array[i];
            array[i] = array[j];
            array[j] = temp;
        }
    }

    static string GetAlternatingString(string s)
    {
        char[] chars = s.ToCharArray();
        Shuffle(chars);
        for (int i = 1; i < chars.Length; i++)
        {
            if (chars[i] == chars[i - 1])
            {
                Array.Sort(chars, i, chars.Length - i);
                break;
            }
        }
        for (int i = 1; i < chars.Length; i++)
        {
            if (chars[i] == chars[i - 1])
            {
                return "-1";
            }
        }
        return new string(chars);
    }
}