.
                                  
                            ­        L
                          o      o   v       o
                       v         e    L         v
                      e             o               e
                    L               v                 L
                    o               e                  o
                   v                L                  v
                    e      ­      o      v             e
                     L           e      L            L
                      o            o   v            o
                        v             e            v
                             e        L        e
                                       o
                                       v
                                       e