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



if __name__ == "__main__" :
	t = []
	u = []
	minStack = []
	s = list( raw_input() )
	size = len( s )
	for i in xrange( size - 1 , -1 , -1 ) :
		if len( minStack ) == 0 or minStack[ len( minStack ) - 1 ] >= s[ i ] :
			minStack.append( s[ i ])
	for i in xrange( len( s ) ) :
		while len( t ) != 0 and minStack[ len( minStack ) - 1 ] >= t[ len( t ) - 1 ]  : 
			u.append( t[ len( t ) - 1 ])
			t.pop()
		if minStack[ len( minStack ) - 1 ] == s[ i ] :
			u.append( s[ i ])
			minStack.pop()
		else :
			t.append( s[ i ] )
	while len( t ) != 0 :
		u.append( t[ len( t ) - 1 ])
		t.pop()
	u = ''.join( u )
	print u
