class P09_String1_Intro_checking {

  public static void main(String[] args) {
    showFrontCharacter(null);
    showFrontCharacter("");
    showFrontCharacter("CS2312");

  }

  private static void showFrontCharacter(String s) {
    if (s!=null && s.length() != 0) {
      System.out.println(s + " starts with " + s.charAt(0));
    } else {
      System.out.println("invalid request");
    }

  }
}