ref: f0f2d452c873255dec4b3359b3f93e349be0f2c5
dir: /sys/games/lib/sudoku/boards/hard-2005-05-23.su/
....185.9 ..54..... ..4.69.27 74....... .1.....5. .......86 57.68.4.. .....76.. 8.319.... 627318549 985472163 134569827 746835912 318926754 259741386 572683491 491257638 863194275