*-----------*
|...|7..|.4.|
|...|.3.|169|
|4..|.9.|.8.|
|---+---+---|
|...|..2|75.|
|7..|9.1|..8|
|.23|4..|...|
|---+---+---|
|.4.|.1.|..6|
|651|.4.|...|
|.8.|..3|...|
*-----------*