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
  
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)