ref: c4603260f8736dbea8d7f47c46e8db0cf1a23fa0
dir: /sys/games/lib/sudoku/boards/medium-2005-05-13.su/
3..4...2. .....58.7 ..79..1.6 .....9... 4..8.1..2 ...5..... 1.5..72.. 9.86..... .6...2..8 381476925 694215837 257938146 516729384 439861572 872543691 145387269 928654713 763192458