docs: public static int Hamming(String first, String second) {
  
          if (first.length() != second.length())
              throw new IllegalArgumentException("The size of string must be the same.");
  
          int diff = 0;
          for (int i = 0; i < first.length(); i++)
              if (first.charAt(i) != second.charAt(i))
                  diff++;
          return diff;
      }