*-----------*
|...|.3.|.5.|
|.4.|2..|..6|
|1..|856|..7|
|---+---+---|
|4.3|52.|.8.|
|.81|...|59.|
|.9.|.83|6.4|
|---+---+---|
|6..|342|..8|
|3..|..8|.6.|
|.1.|.6.|...|
*-----------*