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()

def f(l = 0):
  c = min(s[l:])
  cnt = s[l:].count(c)
  return (c, cnt)

c, cnt = f()
res, t = [], []
for i, e in enumerate(s):
  if e == c:
    res.append(e)
    if cnt > 1:
      cnt -= 1
    else:
      if i == len(s) - 1:
        break
      c, cnt = f(i + 1)
      while len(t) and t[-1] <= c:
        res.append(t[-1])
        t.pop()
  else:
    t.append(e)
print(''.join(res + t[::-1]))
