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

class Program
{
    static string InputPattern = "Input5";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("12");
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("21");
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("1122");
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("999999999");
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        char[] StrArr = InputList[0].ToCharArray();
        char[] DescStr = StrArr.OrderByDescending(X => X).ToArray(); ;

        int ChangeInd1 = -1;
        for (int I = 0; I <= StrArr.Length - 1; I++) {
            if (StrArr[I] != DescStr[I]) {
                ChangeInd1 = I;
                break;
            }
        }
        if (ChangeInd1 == -1) {
            Console.WriteLine(StrArr);
            return;
        }
        int ChangeInd2 = Array.LastIndexOf(StrArr, DescStr[ChangeInd1]);

        char wkSankaku = StrArr[ChangeInd1];
        StrArr[ChangeInd1] = StrArr[ChangeInd2];
        StrArr[ChangeInd2] = wkSankaku;

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