ref: af20ba67460b79f7c4aee7014756205baba29cd5
dir: /sys/games/lib/sudoku/boards/medium-2005-05-16.su/
9...153.. 6..4..... ...9..5.4 54.1..6.. 7.......5 ..3..8.42 4.8..3... .....1..9 ..956...1 924815367 651437928 837926514 542179683 786342195 193658742 418793256 365281479 279564831