ref: a0ba4c1f03a3f99fb17a9edf9b4448db49bb6c46
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