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
import string


def solve(s):
    alpha = {x: i for i, x in enumerate(list(string.ascii_lowercase))}
    t, u = [], []
    s = list(s)[::-1]
    char_count = [0] * 26
    for char in s:
        char_count[alpha[char]] += 1
    while s:
        char = s.pop()
        t.append(char)
        char_count[alpha[char]] -= 1
        m = min([float('inf')] + [i for (i, x) in enumerate(char_count) if x])
        while t and m >= alpha[t[-1]]:
            u.append(t.pop())
    while t:
        u.append(t.pop())

    return ''.join(u)


print(solve(input()))