On my courses we've got homework on site in folders such as:

http://example.com/files/tasks1-edc34rtgfds
http://example.com/files/tasks2-0bg454fgerg
http://example.com/files/tasks3-h1dlkjiojo8
...

Each tasksi-xxxxxxxxxxx is a folder with 11 random characters at the end. And when you view the above URLs in browser you can see Index of /tasksi-xxxxxxxxx with all the files in that folder.

When you view http://example.com/files/ you can see only empty html with words "Hello, world".

The problem is that you can't look into the next task without knowledge of its URL. So for example we've got the URLs for tasks1 and tasks2, and we can't guess what tasks3 URL will be (as we need to know the 11 random characters at the end)

How can I get the list of all directories? (Is there a way to type something like http://example.com/files/task1-aflafjal343/..? or another way?) I want to see all upcoming homework tasks.