struct avl_node *s;

da[k] = 1;
pa[k++] = p;
for (;;)
  {
    da[k] = 0;
    pa[k++] = r;
    s = r->avl_link[0];
    if (s->avl_link[0] == NULL)
      break;

    r = s;
  }
p->avl_data = s->avl_data;
r->avl_link[0] = s->avl_link[1];
p = s;