.      
                                     D
                              i     i a       i
                            a      mo        a
                ­          m       n d        m
                          o          s             o
                          n       D    i          n
                          d       a    m         d
                           s       o    n          s
                            D      d   s         D
                               i       D         i
                                  a    ~     a
                                        ~