*-----------*
|..1|.3.|5..|
|...|..8|7.2|
|...|749|..8|
|---+---+---|
|...|...|.79|
|.23|.9.|86.|
|91.|...|...|
|---+---+---|
|3..|471|...|
|2.5|9..|...|
|..4|.5.|9..|
*-----------*