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