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
import math
import bisect


def getList(method=int):
    return list(map(method, input().split()))


def getInt():
    return int(input())


def hasGreater(c):
    global mp
    for k, v in mp.items():
        if c > k and v:
            return True
    return False


s = [v for v in input()]
t = []
ans = ''
n = len(s)
mp = {chr(ord('a') + i): 0 for i in range(26)}
for v in s:
    mp[v] += 1

for v in s:
    if len(t):
        while len(t) and not hasGreater(t[-1]):
            ans += t.pop()

    t.append(v)
    mp[v] -= 1

while len(t):
    ans += t.pop()

print(ans)
