Formula Question
 

I have a list of advertisements with the following information:

Ad Order Number
Insertion Date

Background information: One ad can run on multiple days, both consecutive
and non-consecutive. Ad count would be as follows:

Ad Order A runs 9/1 - 9/3 consecutively = 1 ad
Ad Order B run 9/1 and 9/3 individually = 2 ads

I would like to count how many individual ads (so with the example above it
would be 3) there are in a specific time frame.....please let me know what
additional informaiton you woudl need to assist me with this problem.