+-------+-------+-------+
| _ _ 2 | _ _ 5 | _ 7 9 |
| 1 _ 5 | _ _ 3 | _ _ _ |
| _ _ _ | _ _ _ | 6 _ _ |
+-------+-------+-------+
| _ 1 _ | 4 _ _ | 9 _ _ |
| _ 9 _ | _ _ _ | _ 8 _ |
| _ _ 4 | _ _ 9 | _ 1 _ |
+-------+-------+-------+
| _ _ 9 | _ _ _ | _ _ _ |
| _ _ _ | 1 _ _ | 3 _ 6 |
| 6 8 _ | 3 _ _ | 4 _ _ |
+-------+-------+-------+
