public boolean firstName(String firstName) {
        if (firstName == null || firstName.isEmpty()) {
            return false;
        }
        if ((int) firstName.charAt(0) < 65 || (int) firstName.charAt(0) > 90) {
            return false;
        }
        for (int i = 1; i < firstName.length(); i++) {
            if ((int) firstName.charAt(i) < 97 || (int) firstName.charAt(i) > 122) {
                return false;
            }
        }
        return true;
    }