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 sys

s = list(sys.stdin.readline().rstrip())

t = []
u = []

X = [0] * 26
for c in s:
	X[ord(c) - 97] += 1
#print X

for c in s:
	i = ord(c) - 97
	X[i] -= 1
	t += c
	while t and sum(X[:ord(t[-1]) - 97]) == 0:
		u += [t.pop()]

while t:
	u += [t.pop()]
print "".join(u)