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C. Minimal string

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputPetya recieved a gift of a string *s* with length up to 10^{5} characters for his birthday. He took two more empty strings *t* and *u* and decided to play a game. This game has two possible moves:

- Extract the first character of
*s*and append*t*with this character. - Extract the last character of
*t*and append*u*with this character.

Petya wants to get strings *s* and *t* empty and string *u* lexigraphically minimal.

You should write a program that will help Petya win the game.

Input

First line contains non-empty string *s* (1 ≤ |*s*| ≤ 10^{5}), consisting of lowercase English letters.

Output

Print resulting string *u*.

Examples

Input

cab

Output

abc

Input

acdb

Output

abdc

Codeforces (c) Copyright 2010-2017 Mike Mirzayanov

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