ref: c7fc69bd6a965a4cb8eca7c9d4a069fb271c68e2
dir: /sys/games/lib/sudoku/boards/medium-2005-02-27.su/
9..6..... .467...2. 7.8.3.... 8.3....5. ..93.47.. .1....6.8 ....4.8.1 .7...639. .....9..6 932651487 146798523 758432169 823167954 569384712 417925638 695243871 274816395 381579246