ref: 23742053f5ee70cd394c33f28f3e6547e9e8e31d
dir: /sys/games/lib/sudoku/boards/easy-2005-03-06.su/
..217..49 ......5.. 1....67.2 ....9..26 .2.4.5.8. 97..6.... 3.47....5 ..8...... 51..392.. 852173649 736942518 149586732 485397126 623415987 971268453 364721895 298654371 517839264