ref: 50d23b6acc6ad659d28ec91ae9e75da2f30d3f9a
dir: /sys/games/lib/sudoku/boards/medium-2005-05-06.su/
....1.5.8 ..1.293.6 ..24..... .6....8.. ..52.47.. ..4....9. .....56.. 5.976.4.. 6.7.4.... 946317528 781529346 352486179 263971854 895234761 174658293 428195637 519763482 637842915