ref: ce1edc34368d192db7d3421673ca98c19cc792b2
dir: /sys/games/lib/sudoku/boards/medium-2005-01-22.su/
.....91.5 .1...3.76 .....189. .5...2... 7.4...9.8 ...5...6. .763..... 48.7...2. 2.19..... 842679135 915483276 367251894 653892741 724136958 198547362 576328419 489715623 231964587