ref: bf2a6f786502026ce4229bc84a6a22e5e55a7c13
dir: /sys/games/lib/sudoku/boards/easy-2005-02-16.su/
67...835. 9..1...6. ..3....2. ..78.1.95 ....6.... 42.5.38.. .3....9.. .8...4..1 .963...74 671428359 952137468 843956127 367841295 518269743 429573816 734615982 285794631 196382574