.

                                       H
                                 a   a v    a
                               v     eH       v
                             e       a v         e
                           a          a             a
                           g        g     r          g
                           r        e     a          r
                            e        t    d         ­ e
                             a        a  y          a
                               t        H           t
                                d       a        d
                                  a     v      a
                                     y  e   y