public static String compare(int a, int b) {
		@SuppressWarnings("unchecked")
		ArrayList<Integer> m1 = (ArrayList<Integer>) information.get(a).getTimeStamp();
		@SuppressWarnings("unchecked")
		ArrayList<Integer> m2 = (ArrayList<Integer>) information.get(b).getTimeStamp();
		int length = m1.size();

		boolean check = true;
		for (int i = 0; i < length; i++) {
			if (m1.get(i) <= m2.get(i))
				continue;
			else {
				check = false;
				break;
			}
		}
		if (check == true)
			return " <- ";

		check = true;
		for (int i = 0; i < length; i++) {
			if (m1.get(i) >= m2.get(i))
				continue;
			else {
				check = false;
				break;
			}
		}
		if (check == true)
			return " -> ";

		return " || ";

	}