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 deque

s = list(input())
s_deque = deque(s)

ch_cnt = {}
for ch in s:
    if ch not in ch_cnt:
        ch_cnt[ch] = 0
    ch_cnt[ch] += 1

t = []
u = ""

while s_deque:
    ch = s_deque.popleft()

    while t and all(t[-1] <= i for i in ch_cnt):
        tmp_ch = t.pop()
        u += tmp_ch
    t.append(ch)
    ch_cnt[ch] -= 1
    if ch_cnt[ch] == 0:
        del ch_cnt[ch]

while t:
    tmp_ch = t.pop()
    u += tmp_ch

print(u)

