/*
 * This code is from "Algorithms in C, Third Edition,"
 * by Robert Sedgewick, Addison Wesley Longman, 1998.
 */
link insertR(link h, Item item)
  { Key v = key(item), t = key(h->item);
    if (h == z) return NEW(item, z, z, 1);
    if (rand() < 1.0*RAND_MAX/(h->N + 1)) 
      return insertT(h, item);
    if less(v, t) h->l = insertR(h->l, item);
             else h->r = insertR(h->r, item);
    return h;
  }
void STinsert(Item item)
  { head = insertR(head, item); }