ref: 47682ee42a1f686dbd3aa9de7375c16f7d3d95e8
dir: /sys/games/lib/sudoku/boards/vhard-2005-04-10.su/
..6.1.... 5....9.84 ..1....7. ..32....5 9.......8 1....46.. .5....8.. 74.5....9 ....4.2.. 496718523 537629184 281453976 863297415 924165738 175834692 659372841 742581369 318946257