.
                                   P
                         E      E  D      E
                       D        P  E         D
                     P             D             P
                    E              P               E
                   D              E                 D
                   P            D   P              P
                    E           E    D            E
                     D          P   E            D
                       P         D  P           P
                         E        ED         E
                             D     P      D
                                     E
                                     D