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 sys import stdin
from collections import deque
input = stdin.readline

s = input().strip()
t = []
u = []

x = deque()
cur_min = "z"
for i in range(len(s)-1, -1, -1):
    cur_min = min(cur_min, s[i])
    x.appendleft(cur_min)
i = 0
while i < len(s):
    if len(t) > 0 and t[-1] <= x[i]:
        u.append(t.pop())
    else:
        target = x[i]
        while s[i] != target:
            t.append(s[i])
            i += 1
        t.append(s[i])
        i += 1
while t:
    u.append(t.pop())
print(*u, sep="")