30b
 +-----------------+
8|         D       |
7|       h     r   |
6|   r     H       |
5|   d r r         |
4| r r E c d       |
3| R D m e     H h |
2|   R R C R C   r |
1|     M     R R R |
 +-----------------+
   a b c d e f g h