[ 6 _ 8 _ 7 _ 5 _ 2 ]
[ _ 5 _ 6 _ 8 _ 7 _ ]
[ _ _ 2 _ _ _ 3 _ _ ]
[ 5 _ _ _ 9 _ _ _ 6 ]
[ _ 4 _ 3 _ 2 _ 5 _ ]
[ 8 _ _ _ 5 _ _ _ 3 ]
[ _ _ 5 _ _ _ 2 _ _ ]
[ _ 1 _ 7 _ 4 _ 9 _ ]
[ 4 _ 9 _ 6 _ 7 _ 1 ]