public static String timeConversion(String s) {
        boolean isAM = false;
        
        if (s.endsWith("AM")) {
            isAM = true;
        }
        
        s = s.substring(0, s.length() - 2);
        int hour = Integer.valueOf(s.substring(0,2));
        
        if (isAM && hour == 12) {
            return "00".concat(s.substring(2));
        } else if (!isAM && hour != 12) {
            return Integer.toString(hour + 12).concat(s.substring(2));
        } else {
            return s;
        }
    }