*-----------*
|..9|8..|...|
|83.|..4|..6|
|...|..9|41.|
|---+---+---|
|.2.|...|89.|
|3..|...|..7|
|.74|...|.6.|
|---+---+---|
|.65|2..|...|
|2..|5..|.49|
|...|..1|6..|
*-----------*