Solved by 15 users: WsemirZ, JohnJones_001, zloy_mipt, pmnox, UdH-WiNGeR, regal, defrager, Rizvanov, Dest, EAA2008, fetetriste, ripatti, dan, vi002, avg79.
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## 3D puzzle

Time limit = 5 second(s)

This problem is about 3D-version 3x3x3 of wellknown 15-puzzle.

Initial position corresponds to

```0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
```

"0" stands for empty cell.

```верхний		средний		нижний
слой 0:		слой 1:		слой 2:

0  1  2	 9 10 11	18 19 20
3  4  5	12 13 14	21 22 23
6  7  8	15 16 17	24 25 26
```

Input Description of position — permutation od numbers {0,1,..,26}.

Output Output IMPOSSIBLE if thereis now way to get initial position.

Output K+1 line if there is way to get initial position by K moves. K may be not minimal one, but less than 500.

The first line has description of given position. Next K lines should contain descriptions of positions.

i-th position should be achiieved from the (i-1)-th position by on move.

 Input#1``` 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ``` Output#1``` 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ```
 Input#2``` 0 2 1 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ``` Output#2```IMPOSSIBLE ```
 Input#3``` 3 1 2 0 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ``` Output#3``` 3 1 2 0 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ```
 Input#4``` 3 1 2 4 13 5 6 7 8 9 10 11 12 16 14 0 25 17 18 19 20 21 22 23 15 24 26 ``` Output#4``` 3 1 2 4 13 5 6 7 8 9 10 11 12 16 14 0 25 17 18 19 20 21 22 23 15 24 26 3 1 2 4 13 5 6 7 8 9 10 11 12 16 14 15 25 17 18 19 20 21 22 23 0 24 26 3 1 2 4 13 5 6 7 8 9 10 11 12 16 14 15 25 17 18 19 20 21 22 23 24 0 26 3 1 2 4 13 5 6 7 8 9 10 11 12 16 14 15 25 17 18 19 20 21 22 23 24 26 0 3 1 2 4 13 5 6 7 8 9 10 11 12 16 14 15 25 17 18 19 20 21 22 23 24 0 26 3 1 2 4 13 5 6 7 8 9 10 11 12 16 14 15 0 17 18 19 20 21 22 23 24 25 26 3 1 2 4 13 5 6 7 8 9 10 11 12 0 14 15 16 17 18 19 20 21 22 23 24 25 26 3 1 2 4 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 3 1 2 0 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ```

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