title: c# DateTime.ParseExact fractional seconds issue
body: <p>I have a scenario where I'm reading values from a file and converting it to <code>DateTime</code>. The problem is that in my time, sometimes I have 5 decimal places for seconds and sometimes 6. 
  For eg, <code>19:23:30.12345</code> and <code>12:13:33.123456</code>. If I have to parse this, I cannot use <code>ss.fffff</code> or <code>ss.ffffff</code>. What do I do?</p>