ref: e2124b109ecb0f5634f036e392d827b6ddebec54
dir: /sys/games/lib/sudoku/boards/medium-2005-05-17.su/
9.......4 6....481. 3.1...2.. ..6.1..4. ...743... .7..2.3.. ..9...7.3 .139....8 7.......2 982157634 657234819 341896275 236518947 198743526 475629381 829461753 513972468 764385192