ref: 457ba087b13a881b013940f6e54c09566ec10ed1
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