ref: 16aaa24c7604b5f9d492796b20179427adb0a91b
dir: /sys/games/lib/sudoku/boards/easy-2005-01-29.su/
...56..18 9.....52. ..5..149. 1.4.3.... .7..4..6. ....9.7.3 .516..8.. .29.....4 78..14... 247569318 916483527 835271496 194736285 372845961 568192743 451627839 629358174 783914652