ref: ab5c4799d95e0d60ca9ebf16dede88cd245e3aaa
dir: /sys/games/lib/sudoku/boards/easy-2005-03-07.su/
2...7.8.6 ..8...4.9 .64.53... ..1..7.9. ...6.5... .5.9..1.. ...73.56. 5.6...2.. 7.2.4...3 215479836 378261459 964853721 421387695 897615342 653924187 149732568 536198274 782546913