.
                                      P
                       ­       o    ow     o
                           w       er         w
                          e          P            e
           ­              r         o   w         r
                         P        e     r          P
                         o        P     o         o
                          w       w  e         w
                            e          r          e
           ­                   r        P        r
                          ­      P     o       P
                                  o   w    o
                                    w !  w
                                        !!!