w = x;
y->pavl_link[0] = x->pavl_link[1];
x->pavl_link[1] = y;
x->pavl_balance = y->pavl_balance = 0;
x->pavl_parent = y->pavl_parent;
y->pavl_parent = x;
if (y->pavl_link[0] != NULL)
  y->pavl_link[0]->pavl_parent = y;