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()
prefmin = ['{'] * (len(s) + 1)
st = []

for i in range(len(s) - 1, -1, -1):
    prefmin[i] = min(s[i], prefmin[i + 1])

for i in range(len(s)):
    while len(st) and st[-1] <= prefmin[i]:
        print(st.pop(), end='')
    if prefmin[i] == s[i]:
        print(s[i], end='')
    else:
        st.append(s[i])

for i in range(len(st) - 1, -1, -1):
    print(st[i], end='')

