w->rb_color = pa[k - 1]->rb_color;
pa[k - 1]->rb_color = RB_BLACK;
w->rb_link[0]->rb_color = RB_BLACK;

pa[k - 1]->rb_link[0] = w->rb_link[1];
w->rb_link[1] = pa[k - 1];
pa[k - 2]->rb_link[da[k - 2]] = w;