ref: e8c3eb87d27f95a9a0b89a93164dba42427659ec
dir: /sys/games/lib/sudoku/boards/easy-2005-01-23.su/
.9..4825. ......7.8 .2...5.1. .6.52...1 3...1...2 7...89.4. .4.8...6. 6.1...... .8573..2. 197348256 534162798 826975413 468523971 359417682 712689345 243891567 671254839 985736124