public List<Integer> mergeSort(List<Integer> num) {

		if (num.size() < 2) {
			return num;
		}

		List<Integer> left = num.subList(0, num.size() / 2);
		List<Integer> right = num.subList(num.size() / 2, num.size());

		return merge(mergeSort(left), mergeSort(right));

	}