ref: f341ae8c777dda2876beb4d4a1c67c4e920595ca
dir: /sys/games/lib/sudoku/boards/vhard-2005-03-17.su/
...91.... 3...2..1. .75..86.. .52...... 6..5.9..7 ......18. ..68..94. .8..5...2 ....94... 264917853 398625714 175348629 852731496 641589237 937462185 526873941 489156372 713294568