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
'''input
cab
'''
s = input()
m = ["z"] * len(s)
m[-1] = s[-1]
c = s[-1]
for x in range(len(s) - 2, -1, -1):
	c = min(c, s[x])
	m[x] = c
i = m.index(min(m))
t = []
y = ""
for x in range(len(s)):
	while t and t[-1] <= m[x]:
		y += t.pop()
	t.append(s[x])
print(y, end="")
for x in t[::-1]:
	print(x, end="")
# s1 = sorted(s)
# t, u = [], []
# for l in s1:
# 	if l in s:
# 		i = s.index(l)
# 		t += s[:i]
# 		del s[:i+1]
# 		u.append(l)
# print("".join(u + t[::-1]))
