Petya 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 lexicographically 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