// Using Java LocalTime class.
    private static String timeConverterLocalTime(String input) {
        DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("hh:mm:ssa");
        DateTimeFormatter outputFormat = DateTimeFormatter.ofPattern("HH:mm:ss");
        LocalTime timeIn24 = LocalTime.parse(input, timeFormatter);
        return timeIn24.format(outputFormat);
    }

    // Using Java algorithmic approach.
    private static String timeConverter(String input) {
        String timeIn24 = "";
        String hours = input.substring(0, 2);
        String timeWithoutPrefix = input.substring(0, input.length() - 2);

        if (input.contains("PM")) {
            if (hours.equals("12")) {
                timeIn24 = timeWithoutPrefix;
            } else {
                int hourIn24 = Integer.parseInt(hours) + 12;
                timeIn24 = String.valueOf(hourIn24).concat(timeWithoutPrefix.substring(2));
            }
        }

        if (input.contains("AM")) {
            if (hours.equals("12")) {
                timeIn24 = "00".concat(timeWithoutPrefix.substring(2));
            } else {
                timeIn24 = timeWithoutPrefix;
            }
        }
        return timeIn24;
    }