public static HashMap<String, Integer> getDifferences(Date begin, Date end)  {
		HashMap<String, Integer> output = new HashMap<>();
		long diff = end.getTime() - begin.getTime();

		output.put("s", (int) diff / 1000 % 60);
		output.put("m", (int) diff / (60 * 1000) % 60);
		output.put("h", (int) diff / (60 * 60 * 1000) % 24);
		output.put("d", (int) diff / (24 * 60 * 60 * 1000));
		return output;
	}

	public static String clockFormat(HashMap<String, Integer> input) {
		String output = "";
		ArrayList<String> units = new ArrayList<>();
		for (String key : input.keySet()) {
			if (input.get(key) > 10) {
				units.add("0" + input.get(key));
			} else {
				units.add(input.get(key) + "");
			}
		}
		for (String unit : units) {
			if (!output.equals("")) {
				output = output + ":" + unit;
			} else {
				output = unit;
			}
		}
		return output;
	}