.
                                   m
                          o      o d      o
                       d         e s          d
                     e             t               e
                    s              m               s
                    t               o                 t
                   m           d   e              m
                    o            s    t              o
                     d          m   o             d
                      e           d  e            e
                        s          s t            s
                           t        m       t
                                     o
                                     d