rem: if (!in_set[c]++) --cardinality;
add: { cardinality -= (!in_set[c]); in_set[c] = true; }
context: card_of_complement (struct Spec_list *s){  int c;  int cardinality = N_CHARS;  SET_TYPE in_set[N_CHARS];  memset (in_set, 0, N_CHARS * sizeof (in_set[0]));  s->state = BEGIN_STATE;  while ((c = get_next (s, NULL)) != -1)    if (!in_set[c]++)      --cardinality;  return cardinality;}