.
                                     P
                           r       r  i        r
                         i          z e          i
                       z            P             z
                      e             r               e
                     P              i                P
                     r           z     e             r
                      i           P     r            i
                        z         i    z            z
                         e         e  P          e
                           P         r          P
                               r      i      r
                                       z
                                       e