ref: 8635cc20b14553f088c937a75e92ebda02cd0c63
dir: /sys/games/lib/sudoku/boards/medium-2005-05-09.su/
..2...... .7....15. .3..95.8. ....1..49 ..17.45.. 34..6.... .9.27..6. .24....9. ......7.. 512847936 879326154 436195287 287513649 961784523 345962871 193278465 724651398 658439712