ref: 1787a8b990236e27d4487ea5ea6e9623b7106b1d
dir: /sys/games/lib/sudoku/boards/easy-2005-04-26.su/
..2816..9 .6..7...2 .7.9...6. .4.2....1 2.......5 9....3.7. .9...8.2. 8...2..4. 6..5971.. 432816759 569374812 178952463 347285691 216749385 985163274 791438526 853621947 624597138