ref: ad7120b2e2f0ed0d226eec1b5ef6fc6b3eebb4ef
dir: /sys/games/lib/sudoku/boards/medium-2005-05-25.su/
4...6.93. 7.2....1. ....43... 6..5..3.. .7.....8. ..5..9..7 ...29.... .9....2.8 .21.8...4 418762935 732958416 956143872 689527341 273416589 145839627 867294153 594371268 321685794