ref: 902bd7ba274c50743a2cb15f4bca7a55b443172e
dir: /sys/games/lib/sudoku/boards/easy-2005-02-14.su/
..2..9.4. 7.....985 6....3.2. 9....1.5. ..58976.. .2.4....8 .5.6....9 876.....3 .9.3..5.. 512789346 734126985 689543721 968231457 145897632 327465198 453612879 876954213 291378564