ref: 52ad5b3ec5138a85e4c976013adbc54642f19b74
dir: /sys/games/lib/sudoku/boards/easy000.su/
.8...5... .....3457 ....7.8.9 .6.4..9.3 ..7.1.5.. 4.8..7.2. 9.1.2.... 8423..... ...1...8. 786945312 219863457 534271869 165482973 327619548 498537126 951728634 842356791 673194285