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(input())
s.reverse()
n = len(s)
min_char = [s[0]]
for i in range(1,n):
    min_char.append(min(s[i],min_char[i-1]))
t = []
u = []
while len(u) < n:
    if len(t)==0:
        t.append(s.pop())
    elif len(s)==0:
        u.append(t.pop())
    else:
        if min_char[len(s)-1] < t[-1]:
            t.append(s.pop())
        else:
            u.append(t.pop())
print(''.join(u))