.

                                    r
                        ­  e      e p        e
                        p        e a          p
                       e           t              e
                      a         r     e           a
                      t         p      e           t
                      P         r      f           p
                       e        o     r           e
                        r        m  a           r
                         f         n  c          f
                          o         e          o
                             r       r        r
                               m   e   m
                                      p
                       ­               e
                                      a
        ­                              t