x x 9  x x 3  x x x
x x 8  x x 7  x 3 x 
1 7 x  x 9 x  5 x 4

x 4 5  x x x  x x 8
x x x  x 8 x  x x x
9 x x  x x x  6 1 x

8 x 2  x 5 x  x 9 6
x 9 x  8 x x  3 x x
x x x  6 x x  7 x x