x 8 6 x x x x x x
x 7 4 x 2 x 9 6 x
x 9 x x 1 x 4 x x

x 4 3 x x 7 x x x
x x 9 6 x 3 8 x x
x x x 9 x x 5 3 x

x x 2 x 6 x x 9 x
x 5 7 x 9 x 1 2 x
x x x x x x 3 5 x