.
                                   F
                          r      r   i       r
                       i          e   n         i
                     e             d              e
                    n              s               n
                    d              F                d
                   s               r                  s
                   F           i         e            F
                   r           n        d            r
                    i            s      F             i
                     e              r                e
                      n             i              n
                        d           e           d
                           s         n        s
                                      d
                                      s