ref: e4b215d77ff0f63eaf42d737a1a4f75d2a2037aa
dir: /sys/games/lib/sudoku/boards/medium-2005-04-13.su/
...7.34.1 .1..4.9.8 ...8..... ..6.3.1.. .8..5..4. ..4.7.3.. .....6... 5.9.8..3. 2.73.4... 895763421 613245978 472819563 726438159 381952647 954671382 138526794 549187236 267394815