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
#! /bin/python

s = input()
resultBase = ""
resultRest = ""
best = len(s) - 1
mini = [0] * len(s)

for i in range(len(s) - 1, -1, -1):
    mini[i] = best
    if s[best] >= s[i]:
        best = i

for i in range(len(s)):
    resultRest += s[i]
    while len(resultRest) > 0 and resultRest[-1] <= s[mini[i]]:
        resultBase += resultRest[-1]
        resultRest = resultRest[:-1]
    
print(resultBase + resultRest[::-1])
