How to get the session ID from mobile web querystring?

Hi ,

Anyone know how to retrieve the value of the session ID from the mobile web querystring ?
For example:

http://localhost/(c2jsffj5kzl03045wtjq0iz3)/index.aspx

How can i retrieve the "c2jsffj5kzl03045wtjq0iz3" and store it in a variable ?

For your information, what i want to do in my system is to create a .txt file which has the SessionID as the name of the txt file , so that no repeated crashing of file names from the clients.

This is the only way i can think of , which is to use the session ID as the name , any alternative ways to do so ?