28b
 +-----------------+
8|                 |
7|             r   |
6|       r h r     |
5|   d r r D H     |
4| r r E c d h     |
3| R D m e     H   |
2|   R R C R C c r |
1|     M     R R R |
 +-----------------+
   a b c d e f g h