ref: f596580cba7c5b7bae84ee7cd83d2b2a438a1e9b
dir: /sys/games/lib/sudoku/boards/medium003.su/
..4...... ....3...2 39.7...8. 4....9..1 2.98.13.7 6..2....8 .1...8.53 9...4.... ......8.. 124986735 867435912 395712684 478359261 259861347 631274598 712698453 983547126 546123879