.

                                    P
                          o      om        o
                       m        Po           m
                      P          mP             P
                     o             o                o
                    m            m                m
                     P           P   o              P
                      o          m  P             o
                       m         o m           m
                         P         P o          P
                           o        m         o
                              m    P     m
                                     o
                                     m