ref: 75f5fdbb0df902d8d7e16a4489a04d92493eacae
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