.
                                     P
                            o      o s       o
                          s         t r           s
                         t          om            t
                         r        a      n         r
                         o        t       i          o
                          m       c    i         m
                           a        s m         a
                             n        P         n
                               t        o        t
                                  i     s      i
                                     c  t  c
                                         ●