date substraction issue

The following code is producing a difference of "300000".
I am trying to get "05".   What am I doing wrong or what additional step do I need?

Code Snippet:

          String Time1 = "2011-09-21T22:30:00Z";
          String Time2 = "2011-09-21T22:35:00Z";
          DateFormat dfm = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
         
          try {
             long a = dfm.parse(Time1).getTime();
             long b = dfm.parse(Time2).getTime();
             long c = (b-a);
             Long diff = new Long(c);
             System.out.println(forecastTime +"-" + currentTime + "=" + diff.toString());
          } catch (Exception e) {
             e.printStackTrace();
          }