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
from collections import deque
S = input()
mn = [ 300 for i in range( len( S ) ) ]
for i in range( len( S ) - 1, -1, -1 ):
  if i == len( S ) - 1:
    mn[ i ] = ord( S[ i ] )
  else:
    mn[ i ] = min( mn[ i + 1 ], ord( S[ i ] ) )
ans = ""
dq = deque()
for i in range( len( S ) ):
  dq.append( ord( S[ i ] ) )
  while len( dq ) and ( i + 1 == len( S ) or dq[ len( dq ) - 1 ] <= mn[ i + 1 ] ):
    ans += chr( dq[ len( dq ) - 1 ] )
    dq.pop()
print( ans )
