static void post_multi(L<S> a, L<S> b, L<S> c) {
  for (S _a : a)
    for (S _b : b)
      for (S _c : c)
        post(_a, _b, _c);
}

static void post_multi(S a, S b, L<S> c) {
  post_multi(ll(a), ll(b), c);
}