.
                                
                                      
                                 NiN   
                         i       c   e         i
                      c          N i               c
                   e              ce                 e
                 N              e   N                e
                 i               i       c               N
                 c              e      N                i
                  e              i      c                c
                    N             e  N              e
                       ii             i             N
                            c         c       i                
                                       e
                                      N
                                       i
                                       c
                                       e