Minimal string

1000ms

262144K

Description:

Petya recieved a gift of a string s with length up to 10⁵ 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| ≤ 10⁵), consisting of lowercase English letters.

Output:

Print resulting string u.

Sample Input:

cab

Sample Output:

abc

Sample Input:

acdb

Sample Output:

abdc

Informação

Provedor Codeforces

Código CF797C