.
                                      R
                       ­      e      e a       e
                           a        s o          a
                          s           n             s
                         o        R     e          o
                         n        a      s          n
                          R        o   n           R
                           e          R             e
                            a         e            a
                              s        a          ­s
                                  o    l     o
                                    
                                        N