ref: 56c212c010af4d0e18454699699eb65d08704af0
dir: /sys/games/lib/sudoku/boards/easy-2005-03-08.su/
.425....6 9.17...5. .5...4.31 ....2.5.. ...3.1... ..3.7.... 73.1...6. .6...73.9 1....524. 342519786 981763452 657284931 416928573 879351624 523476198 734192865 265847319 198635247