ref: 83efe2f157743feb3f5b6bbb1e34ee56ab3a6dad
dir: /sys/games/lib/sudoku/boards/hard-2005-03-14.su/
4..57.... ..98..57. .....1..6 .3....86. ..86.91.. .65....2. 8..4..... .94..36.. ....85..7 481576392 629834571 573291486 932157864 748629135 165348729 857462913 294713658 316985247