public Nodo Borrar() {
    Nodo aux = h;

    if (h == t) h = t = null;
    else h = h.GetLigaDer();
    return aux;
  }
 public void Listar() {
   Nodo q;
   for (q = h; q != null; q = q.GetLigaDer()) System.out.println(q.GetInfo());
 }