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()

min_s = [chr(123)] * len(s)
min_s[-1] = s[-1]

for i in range(len(s)-2, -1, -1):
    #print(i)
    min_s[i] = min(s[i], min_s[i+1])
    
t = []
u = []

for i in range(len(s)):
    
    if len(t) and min_s[i] >= t[-1]:
        while len(t) and t[-1] <= min_s[i]:
            u.append(t.pop())
    
    
    if s[i] == min_s[i]:
        while len(t) and t[-1] <= s[i]:
            u.append(t.pop())
        u.append(s[i])
    else:
        t.append(s[i])
        
u = u + t[::-1]
assert len(u) == len(s)
print(''.join(u))
