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
ct = [0] * 26
string = input().strip()
for i in string:
    ct[ord(i) - ord('a')] += 1
t, u = [], []
for i in string:
    t.append(i)
    ct[ord(i) - ord('a')] -= 1
    while t and sum(ct[:ord(t[-1]) - ord('a')]) == 0:
        u.append(t.pop())
print("".join(u))




