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 = input()
m = ['z' for i in range(len(s))]
m[-1] = s[-1]
c = s[-1]
for i in range(len(s) - 2, -1, -1):
    if s[i] < c:
        c = s[i]
    m[i] = c
ind = m.index(min(m))
l = []
res = ''
for i in range(len(s)):
    while l and l[-1] <= m[i]:
        res += l.pop()
    l.append(s[i])
print(res + ''.join(map(str, (l[::-1]))))
