*-----------*
|7..|..4|.2.|
|.54|.3.|.8.|
|...|..9|...|
|---+---+---|
|3.7|..1|..8|
|861|...|293|
|5..|8..|1.6|
|---+---+---|
|...|3..|...|
|.8.|.9.|41.|
|.7.|1..|..9|
*-----------*