ref: 877989481513a00a80f3d58aed2de68744b7b51f
dir: /sys/games/lib/sudoku/boards/medium-2005-05-10.su/
..5...14. 2..86...3 .8.5..... .....3.7. .5.621.8. .3.9..... .....9.3. 4...85..6 .17...4.. 675392148 241867953 389514762 928453671 754621389 136978524 562149837 493785216 817236495