ref: 37f8f8e3e43a4ac6ae65609b8ae7805a04ffe6e7
dir: /sys/games/lib/sudoku/boards/hard-2005-03-26.su/
..8..457. ......... .1..726.3 .....8.1. .62.1.84. .8.5..... 5.169..3. ......... .498..7.. 238164579 796385124 415972683 957248316 362719845 184536297 521697438 873451962 649823751