As an experiment the Educational Codeforces Round 33 will be rated for Div. 2. ×

C. Minimal string
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

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.

Examples
Input
cab
Output
abc
Input
acdb
Output
abdc