ref: 8f5ab25e8696f51f2be8a6743edc2de68c9451d6
dir: /sys/games/lib/sudoku/boards/medium-2005-05-12.su/
.95...... 8..3..1.9 1.3.58... 4.71..... .3.....7. .....73.1 ...81.6.7 6.9..2..3 ......51. 295741836 874326159 163958724 427183965 931465278 586297341 352814697 619572483 748639512