A simple statistical test if a set of 1000 documents is homogeneous

I have a simple statistical question and hope someone here has a quick answer.

I have a set of 200 documents, each document should contain exactly 3 pages. My assumption is that all 100% of those documents have 3 pages. I want to take a sample that would statistically confirm that that set is homogeneous, which means that all documents have exactly 3 pages. If I find even one document in a sample having != 3 pages I would know my set is in-homogeneous.

How many documents do I have to look at to be 80% sure my set is homogeneous? Should I have more then 200 documents in my base set, for instance 1000?