ref: 23620b2e70e9de0ce31c6f4f21926a044c5deabc
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