*-----------*
|..1|...|.7.|
|3.5|.8.|...|
|8..|1.2|...|
|---+---+---|
|.64|8.9|..2|
|...|...|...|
|9..|5.1|36.|
|---+---+---|
|...|3.6|..8|
|...|.7.|2.5|
|.1.|...|6..|
*-----------*