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 collections import Counter, deque

S = input()
T = deque([])
ans = ""

cnt = Counter(S)

for i,s in enumerate(S):
    T.append(s)
    cnt[s] -= 1
    while T:
        smaller = 0
        tmp = T[-1]
        for key in cnt.keys():
            if key < tmp and cnt[key] > 0:
                smaller = 1
                break
        if smaller:
            break
        else:
            ans += T.pop()
            
print(ans)