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
s = list(map(ord, list(input())))
n = len(s)
t = []
u = ""
arr = [0]*26
for i in s:
    arr[i-97] += 1

for i in s:
    arr[i - 97] -= 1
    t.append(chr(i))
    while t and sum(arr[:ord(t[-1])-97]) == 0:
        u += t.pop()

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