ref: 2d56837b2fabf6a7cc11f02b51f20a1e35128c57
dir: /sys/games/lib/sudoku/boards/medium-2005-05-20.su/
.4.83.7.9 ......24. 9.5...... 5...8...6 ..49.63.. 3...4...5 ......5.2 .53...... 8.9.21.3. 641832759 738695241 925714863 597283416 184956327 362147985 416378592 253469178 879521634