Comparing a Search Cursor list to number of PDFs Created.

I need some help on my program. I have the parameters set to ask user to pick an mxd and the folder where those data driven PDFs are located. I started with Search Cursor to create a list from the Sheet_ID field of an mxd. To get total number of pages of that mxd. Now I need to write in for the program to compare the list created from the Sheet numbers to the number of PDFs created and tell me if there is a difference in the total count. For Example: If there are 1 out of 11 sheets for the mxd, then there should be 11 PDFs created and so on. MY code is below:

#Purpose: Compares SheeID field to the toal PDFs created from Data Driven Pages Program

Import arcpy, os, string, sys

#Make parameters for people to choose mxd and folder of PDFs to compare
mxdList = string.split(arcpy.GetParameterAsText(0), ";")
dir = arcpy.GetParameterAsText(1)

#Use Search Cursor to go through Attribuite Table to get Sheet number info
rows = arcpy.SearchCursor(mxdList, "Sheet_ID")

#Use list from Sheet_ID field to match the number of PDFs created to get difference