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()

def get(i):
	m = min(s[i:])
	c = s[i:].count(m)
	return m, c

m, c = get(0)
t, ans = [], []

for i, j in enumerate(s):
	if j == m:
		ans.append(j)
		if c > 1:
			c -= 1
		else:
			if i == len(s) - 1:
				break
			else:
				m, c = get(i + 1)
				while len(t) and t[-1] <= m:
					ans.append(t.pop())
	else:
		t.append(j)

print(''.join(ans + t[::-1]))