ref: bb95002c2d47ab00764a183c200c7fd9ecb3c12a
dir: /sys/games/lib/sudoku/boards/easy-2005-02-12.su/
.28..3... 9.4.6...2 36..92... 1....698. ......... .972....5 ...62..57 7...1.2.9 ...8..13. 528173694 974568312 361492578 142756983 635984721 897231465 413629857 786315249 259847136