function greet(): string
{
  $letters = range('A', 'Z');
  $needed  = ['H', 'E', 'L', 'L', 'O', 'W', 'O', 'R', 'L', 'D' ];
  $string = "";
  foreach ($needed as $needed_letter)
  {
      foreach ($letters as $letter)
      {
          if ($needed_letter == $letter)
          {
              $string .= $needed_letter;
          }
      }
  }
  return strtolower(substr($string, 0, 5)) . ' ' . strtolower(substr($string, 5)) . '!';
}