public void print() {
        int rings = Math.max(Math.max(tower[0].size(), tower[1].size()), tower[2].size());

        for (int i = rings; i > 0; i--) {
            for (int j = 0; j < 3; j++) {
                if (tower[j].size() >= i) {
                    System.out.print(tower[j].elementAt(i - 1) + " ");
                } else {
                    System.out.print("  ");
                }
            }
            System.out.println("");
        }
    }