.
                                     cat
                               k    cat     k
                            i        cat         i
                          n          k             n
                         c            i               c
                         a         n     c          a
                         t          a      t           t
                         k          k    i           k
                          i           n  c           i
                           n          a t          n
                             c          k          c
                                a       i        a
                                   t    n     t