.

                                      C
                            a      a  n      a
                          n        d  y        n
                        d            C             d
                        y            a               y
                       C             n               C
                       a             d                a
                       n          y     C            n
                       d          a      n           d
                       y           d     y            y
                         C          C   a            C
                          a            n             a
                            n          d           n
                              d        y        d
                                  y           y