ref: 53fbb0515159465421053c3165b1aa9da196aa4d
dir: /sys/games/lib/sudoku/boards/easy-2005-03-11.su/
9.5.7...1 ...52.9.. 7....9..3 ..4.9..32 ..6...8.. 27..3.6.. 5..2....8 ..2.47... 1...6.7.9 965374281 438521976 721689543 854796132 316452897 279138654 597213468 682947315 143865729