Copy multiple links from a website

I want to create an app that randomly access pages from another site. This site has more than 40,000 pages and does not have an api.

How can I collect the url of all these 40,000 pages? Copy and paste will be eternal.

All of these pages follow the same structure, similar to http://ift.tt/2kfJjyB, http://ift.tt/2kCueKS, etc