ref: c2a5d7e3f28e86aeef1e4e37e2b88e46af90b62c
dir: /sys/games/lib/sudoku/boards/easy-2005-01-21.su/
.6234.75. 1....56.. 57.....4. ....948.. 4.......6 ..583.... .3.....91 ..64....7 .59.8326. 962341758 148975623 573268149 321694875 487512936 695837412 834726591 216459387 759183264