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