Problem:
Score : 300 points

Problem Statement

Gotou just received a dictionary. However, he doesn't recognize the language used in the dictionary. He did some analysis on the dictionary and realizes that the dictionary contains all possible diverse words in lexicographical order.

A word is called diverse if and only if it is a nonempty string of English lowercase letters and all letters in the word are distinct. For example, atcoder, zscoder and agc are diverse words while gotou and connect aren't diverse words.

Given a diverse word S, determine the next word that appears after S in the dictionary, i.e. the lexicographically smallest diverse word that is lexicographically larger than S, or determine that it doesn't exist.

Let X = x_{1}x_{2}...x_{n} and Y = y_{1}y_{2}...y_{m} be two distinct strings. X is lexicographically larger than Y if and only if Y is a prefix of X or x_{j} > y_{j} where j is the smallest integer such that x_{j} \neq y_{j}.

Constraints

1 \leq |S| \leq 26

S is a diverse word.

Input

Input is given from Standard Input in the following format:

S

Output

Print the next word that appears after S in the dictionary, or -1 if it doesn't exist.

Sample Input 1

atcoder

Sample Output 1

atcoderb

atcoderb is the lexicographically smallest diverse word that is lexicographically larger than atcoder. Note that atcoderb is lexicographically smaller than b.

Sample Input 2

abc

Sample Output 2

abcd

Sample Input 3

zyxwvutsrqponmlkjihgfedcba

Sample Output 3

-1

This is the lexicographically largest diverse word, so the answer is -1.

Sample Input 4

abcdefghijklmnopqrstuvwzyx

Sample Output 4

abcdefghijklmnopqrstuvx

Solution in Python (3.4.3) (judge verdict: Wrong Answer)

# -*- coding: utf-8 -*-

# 単語
keyword = input()
# 全アルファベットのリスト
word_list = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]

ans_word = ""
ans_ltr = ""
# アルファベットを順番に検索
for ltr1 in word_list:
	# 一致する文字が見つからなかった所で候補の文字にしてループを抜ける
	if keyword.find(ltr1) == -1:
		ans_ltr = ltr1
		break
ans_word = keyword + ans_ltr

# 文字数が最大の26だった時の処理
if len(ans_word) == 26:
	# アルファベットを順番に検索
	for ltr1 in word_list:
		# 今度はzの手前までの部分から候補文字を決める
		if ans_word[0:ans_word.find("z")].find(ltr1) == -1:
			ans_ltr = ltr1
			break
	# zの手前の文字を候補文字に置換
	ans_word = ans_word[0:ans_word.find("z") - 1] + ans_ltr

# 最後の単語
if ans_word == keyword:
	ans_word = "-1"

print(ans_word)