.
                                   F
                            a    a c     a
                          c      e F       c
                         e       a c         e
                        F      e      F       F
                        a      c       e       a
                         c      e      F       c
                          e      a    c        e
                           F        e         F
                               a     •      a
                                      c
                                      e