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, t, u = input(), [], ''
j, n = 0, len(s)
p = ['|'] * (n + 1)
for i in range(n, 0, -1): p[i - 1] = min(s[i - 1], p[i])
while j < n:
    if t and t[-1] <= p[j]: u += t.pop()
    else:
        k = p[j]
        while p[j] == k:
            if s[j] == p[j]: u += s[j]
            else: t += [s[j]]
            j += 1
print(u + ''.join(t[::-1]))