*-----------*
|...|..4|..8|
|2..|81.|...|
|1..|..6|5..|
|---+---+---|
|..7|.8.|..4|
|82.|...|.61|
|6..|.5.|9..|
|---+---+---|
|..2|9..|..6|
|...|.68|..9|
|7..|3..|...|
*-----------*