ref: c247ce1c3301222ccd445d3479c29f7eb0e9bfc4
dir: /sys/games/lib/sudoku/boards/medium-2005-01-31.su/
1.8..4... ..9....1. .6.19.74. 2...7.... .87.3.46. ....6...7 .74.53.2. .3....9.. ...8..6.3 158724396 749386512 362195748 296478135 587231469 413569287 674953821 835612974 921847653