.
                                    F
                          e       em        e
                        m        me         m
                      m          F e            m
                      e            m               e
                     F          m    e             F
                     e          F      e             e
                      m        m   m           m
                       m        e     F          m
                          e       e   m         e
                            F      me        F
                                      F