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 sys

s = input()
n = len(s)
smallest = ['']*(n-1) + [s[-1]]
for i in range(n-2, -1, -1):
    smallest[i] = min(smallest[i+1], s[i])

t, u = [], []

for i in range(n):
    while t and t[-1] <= smallest[i]:
        u.append(t.pop())
    if s[i] == smallest[i]:
        u.append(s[i])
    else:
        t.append(s[i])

u += t[::-1]
print(*u, sep='')
