| A | B |
| 1 | X |
| 2 | X X |
| 3 | X X X |
| 4 | X X X X |
| 5 | X X X X X |
| 6 | X X X X X X |
| 7 | X X X X X X X |
| 8 | X X X X X X X X |
| 9 | X X X X X X X X X |
| 10 | X X X X X X X X X X |
| 11 | X X X X X X X X X X O |
| 12 | X X X X X X X X X X O O |
| 13 | X X X X X X X X X X O O O |
| 14 | X X X X X X X X X X O O O O |
| 15 | X X X X X X X X X X O O O O O |
| 16 | X X X X X X X X X X O O O O O O |
| 17 | X X X X X X X X X X O O O O O O O |
| 18 | X X X X X X X X X X O O O O O O O O |
| 19 | X X X X X X X X X X O O O O O O O O O |
| 20 | X X X X X X X X X X O O O O O O O O O O |