ref: 5030157da9e89da53739b13c36942a5355de669f
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