Count unique members of Exchange Distribution Lists

Need a console application that reads in a text file containing a list of exchange distribution lists. For each distribution list in the text file: 1. Open the distribution list 2. Count the unique members (note that some distribution lists contain other distriution lists that also need to be opened and recursed) After all the DLs have been processed, write out a single new file that includes: 1. DL name and unique member count This should be built in Visual Studio 2010 and C# as a console application. A winform app is fine too, just keep it simple. This will run against Exchange 2010. Office 2010 is installed on the client machine. I think there are? a few? ways to do this - using the Exchange web service, using the Outlook object model, etc. I'm looking for whatever provides a performant and robust implementation.