r->tavl_link[0] = p->tavl_link[0];
r->tavl_tag[0] = p->tavl_tag[0];
r->tavl_balance = p->tavl_balance;
if (r->tavl_tag[0] == TAVL_CHILD)
  {
    struct tavl_node *x = r->tavl_link[0];
    while (x->tavl_tag[1] == TAVL_CHILD)
      x = x->tavl_link[1];
    x->tavl_link[1] = r;
  }
pa[k - 1]->tavl_link[da[k - 1]] = r;
da[k] = 1;
pa[k++] = r;