class Fifty {
  public static void main(String[] args) {

    String s = "Hello", t = "World";

    System.out.println( "42. " + (s.length() + t.length()                ) );
    System.out.println( "43. " + (s.substring(1, 2)                      ) );
    System.out.println( "44. " + (s.substring(s.length() / 2, s.length())) );
    System.out.println( "45. " + (s + t                                  ) );
    System.out.println( "46. " + (t.substring(0, 1) + s.substring(1, 4)  ) );

  }
}