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 defaultdict


def check(c):
    global freq
    for val in freq:
        if freq[val] > 0:
            if ord(c) > ord(val):
                return False
    return True


freq = defaultdict(int)
s = input().strip()
for i in s:
    freq[i] += 1
stack = []
res = ''
for i in s:
    stack.append(i)
    freq[i] -= 1
    while stack and check(stack[-1]):
        f = 1
        res += stack.pop()
while stack:
    res += stack.pop()
print(res)