.
                                  B
                          e     e a      e
                        a       v e        a
                       v          r           v
                       e        B  e          e
                       r        a    v         r
                       B       e     r        B
                        e       B    e       e
                          a       a v       a
                            v       e       v
                                e    •     e
                                     R