.

                                     M
                            a      a d      a
                         d         n e         d
                       n             s              n
                      e              s          ­       e
                     s               M                  s
                    M          a        d   ­          M
                    a           n         e              a
                     d           s        s              d
                       n              M               n
                         e             a               e
                            s          d            s
         ­                       s      n       s
                                        e
                     ­                   s
                                        s