ref: f0f2d452c873255dec4b3359b3f93e349be0f2c5
dir: /sys/games/lib/sudoku/boards/medium-2005-04-25.su/
.2...6.8. 93.78.... ..64....7 ...2..4.. ..26.35.. ..1..7... 6....48.. ....39.56 .7.1...9. 427396185 935781642 186425937 769258413 842613579 351947268 693574821 214839756 578162394