.

                                    M
                        ­  i        i   s        i
                       s           e   r          s
                     e               y                e
                   r                 M                 y
                  M                 i                    M
                   i                  s                     i
                   s            e          r              s
                    e   ­        y        M             e
                      r            i     s              r
                         y            e             y
                           M         y         M
                                       M      
                                        i
                                        s
                      ­                  e
                                        r
   ­                                     y