ref: c325c491f61696e81ab0ee9e6aea840c3636ed3d
dir: /sys/games/lib/sudoku/boards/hard-2005-04-24.su/
1.......8 4...3.5.. .831...47 .....5.9. .32...46. .5.2..... 96...813. ..8.2...6 3.......4 195467328 476832519 283159647 741685293 832791465 659243781 964578132 518324976 327916854