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)   ); 

  } 
}