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
str = list(input().strip())
alphabet = [0] * 26
t = []
u = []


def findFirst():
    for index, val in enumerate(alphabet):
        #print(index, val)
        if val > 0:
            return index
    else:
        return False


i = 0
size = len(str)
while i < size:
    alphabet[ord(str[i]) - 97] += 1
    i += 1

i = 0
while i < size:

    t.append(str[i])
    count = 0
    while len(t):
        index = findFirst()
        alphabet[ord(t[-1]) - 97] -= 1
        val = chr(index + 97)
        if t[-1] == val:
            u.append(t.pop())
            if len(t):
                count += 1
                alphabet[ord(t[-1]) - 97] += 1
        else:
            break

    i += 1

while len(t):
    u.append(t.pop())

for item in u:
    print(item, end="")

print()
