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
from sys import stdin
from collections import *
from copy import copy
infile = stdin
word = list(infile.readline().strip())
word.reverse()
T = []
result = []
N = len(word)
best = copy(word)
for i in range(1, N):
    best[i] = min(best[i], best[i-1])

while word or T:
    if not T:
        T.append(word.pop())
    elif not word:
        result.append(T.pop())
    elif T[-1] > best[len(word)-1]:
        T.append(word.pop())
    else:
        result.append(T.pop())
print ''.join(result)
    