ref: 56c212c010af4d0e18454699699eb65d08704af0
dir: /sys/games/lib/sudoku/boards/easy-2005-02-04.su/
5..4.1... .7...9... 496.3..8. 825.6.1.. 7.......6 ..1.9.248 .1..5.634 ...8...1. ...1.6..9 582471963 173689425 496532781 825364197 749218356 631795248 218957634 967843512 354126879