How to get the value of root element in C#

How can we read the attribute value of root element of xml? I am using the following code

<?xml version="1.0" encoding="utf-8"?>    
<!DOCTYPE article PUBLIC "-//NPGSJ//DTD full length article DTD version  
[
<!ENTITY xobx1 SYSTEM "abcx1.pdf" NDATA pdf>
]
<article id="abc" type="a">
<fm>
</fm>
<article>

I need to read this xml file and want to store the attribute value of article tag in some string to check the category of an article .

Please guide