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()
c = ['z'] * (len(s)+1)
for i in range(len(s)-1,-1,-1):
    c[i] = min(s[i], c[i+1])
    # print(i, "c[i] is ", c[i])
l = []
j = 0
while len(l) > 0 or j < len(s):
    if len(l) > 0 and l[len(l)-1] <= c[j]:
        # print("c[j] is",c[j])
        print(l[len(l)-1], end="")
        l.pop()
    else:
        l.append(s[j])
        # print(s[j])
        j += 1




