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