ref: bf2a6f786502026ce4229bc84a6a22e5e55a7c13
dir: /sys/games/lib/sudoku/boards/easy-2005-03-10.su/
.61....7. ...6.839. ....1..8. 2..38..14 ...4.5... 38..91..7 .5..4.... .387.9... .1....75. 861934275 547628391 923517486 275386914 196475823 384291567 759142638 638759142 412863759