ref: 056eb9f7d8b1a577f7029e3d0e6d40cf6c2e86b0
dir: /sys/games/lib/sudoku/boards/medium-2005-04-18.su/
6........ ..854.3.7 ..1.9..4. ...15..6. ..57.81.. .4..39... .5..1.8.. 9.3.675.. ........9 634871952 298546317 571392648 829154763 365728194 147639285 452913876 983467521 716285439