ref: ad7120b2e2f0ed0d226eec1b5ef6fc6b3eebb4ef
dir: /sys/games/lib/sudoku/boards/medium-2005-01-24.su/
..6...7.. .2.5..4.6 4.93...2. 167..8... ....4.... ...2..519 .4...91.3 7.3..2.8. ..8...2.. 536824791 821597436 479361825 167958342 295143678 384276519 642789153 753612984 918435267