ref: ae61eb9381f6b0c70e1c52bf2c2b7f4cd0b5bb6f
dir: /sys/games/lib/sudoku/boards/easy-2005-02-10.su/
26.3....5 .8..723.. .....91.. ....31..8 34.5.8.71 1..49.... ..59..... ..681..5. 8....5.29 261384795 589172364 734659182 697231548 342568971 158497236 475926813 926813457 813745629