ref: 0541a434cb9cfd1a776f1ef29de3a8a7aa1d9b99
dir: /sys/games/lib/sudoku/boards/medium-2005-03-18.su/
...1254.. ..84..... 42.8..... .3.....95 .6.9.2.1. 51.....6. .....3.49 .....72.. ..1298... 976125438 158436927 423879156 234761895 867952314 519384762 782513649 395647281 641298573