/*
 * This code is from "Algorithms in C, Third Edition,"
 * by Robert Sedgewick, Addison Wesley Longman, 1998.
 */
link balanceR(link h)
  { 
    if (h->N < 2) return h;
    h = partR(h, h->N/2);
    h->l = balanceR(h->l); 
    h->r = balanceR(h->r);
    return h;
  }

void BSTbalance()
  { head = balanceR(head); }