Can we write code to count pages in a file irrespective of its type?

[discusshere]

Hello,
I have to count the number of pages in the document that I am uploading. This document can be a word file, xls, txt or pdf. I have my code working for pdf but not for other types. Here is the code that works for pdf- it uses regex

System.IO.FileStream fs = new System.IO.FileStream(filepath, System.IO.FileMode.Open, System.IO.FileAccess.Read);
                System.IO.StreamReader r = new System.IO.StreamReader(fs);
                string text = r.ReadToEnd();

                System.Text.RegularExpressions.Regex regx = new System.Text.RegularExpressions.Regex(@"/Type\s*/Page[^s]");
                System.Text.RegularExpressions.MatchCollection matches = regx.Matches(text);
                noOfPages = matches.Count;

please help me with this. I am totally stuck.