*-----------*
|2..|...|6..|
|...|564|...|
|4..|2..|.9.|
|---+---+---|
|..6|.3.|579|
|...|189|...|
|943|.5.|8..|
|---+---+---|
|.7.|..6|..5|
|...|875|...|
|..9|...|..6|
*-----------*