-------------
|   |   |7  |
| 6 | 5 | 4 |
|   | 2 |  9|
-------------
|   |7  |  8|
|  4|  6|   |
| 5 |  9|  3|
-------------
|   | 3 |1  |
|  2|8 4|  5|
|  9|   | 6 |
-------------
