ref: 8635cc20b14553f088c937a75e92ebda02cd0c63
dir: /sys/games/lib/sudoku/boards/medium-2005-02-25.su/
3.....9.. 67.4....1 4...98... 5....7..6 .3.6.1.7. 2..9....5 ...21...9 7....6.32 ..3.....8 382165947 679432581 451798623 514327896 938651274 267984315 846213759 795846132 123579468