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 = raw_input()
l = len(s)
minSoFar = [0] * l
minSoFar[l-1] = s[l-1]
for i in xrange(l-2, -1, -1):
    if s[i] <= minSoFar[i+1]:
        minSoFar[i] = s[i]
    else:
        minSoFar[i] = minSoFar[i+1]
t, u = [], []
for i, ch in enumerate(s):
    t.append(ch)
    while t and i+1 <= l-1 and t[-1] <= minSoFar[i+1]:
        u.append(t.pop())
while t:
    u.append(t.pop())
print ''.join(u)
