Check String if the format is "yyyy-MM-dd h:mm:ss" in VB.NET

Check String if the format is "yyyy-MM-dd h:mm:ss" in VB.NET

How to check if the given string is in a valid customized format
"yyyy-MM-dd h:mm:ss"?
For example:
2013-09-09 05:25:40
is in a valid format.
and
09-09-2013 05:25:40
is invalid format.