The owner of a casino for New Russians has a very refined sense of beauty. For example, after a game there remain two piles with the same number of cards on the table, and the owner likes the cards to be arranged into two piles according to the color: one pile with red cards and the other with black cards. Of course, this is done not by the owner himself, but by a croupier. The owner just likes to watch the process. The croupier takes a card from the top of one of the initial piles and puts it into one of the new piles; this is repeated until all the cards from the initial piles are transferred. The owner doesn't like it if one of the resulting piles grows faster than the other. At each moment the resulting piles must not differ in size by more than one card; a bigger difference would contradict the owner's sense of beauty. Help the croupier to arrange the cards according to the tastes of his owner.
Input
The first line of the input contains the number N of cards in each of the piles (4 ≤ N ≤ 1000). Each of the next two lines contains N digits 0 or 1 describing the piles: 1 denotes a redsuit card and 0 denotes a blacksuit card. The cards in a pile
are described from the top to the bottom. There are in total N red and N black cards in the two piles.
Output
Output a line containing 2N digits 1 or 2, which describes the process of transferring the cards. Each number shows the number of the pile from which a card is taken. If it is impossible to perform this task according to the given rules, output "Impossible".
Samples
input  output 

4
0011
0110
 22121112

4
1100
1100
 Impossible

Problem Author: Leonid Volkov, Stanislav Vasilyev
Problem Source: QuarterFinal of XXXI ACM ICPC  Yekaterinburg  2006