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

class Program
{
    static void Main()
    {
        char[] N = Console.ReadLine().ToCharArray();

        int idx = Array.LastIndexOf(N, N.Max());

        for (int i = 0; i < N.Length; i++)
        {
            if (N[i] < N[idx])
            {
                char w = N[i];
                N[i] = N[idx];
                N[idx] = w;
                break;
            }
        }

        Console.WriteLine(new string(N));
    }
}