r->rtrb_link[1] = p->rtrb_link[1];
r->rtrb_rtag = p->rtrb_rtag;
t = r->rtrb_color;
r->rtrb_color = p->rtrb_color;
p->rtrb_color = t;
pa[k - 1]->rtrb_link[da[k - 1]] = r;
da[k] = 0;
pa[k++] = r;
