I whine a lot about the kinds of challenges that get posted elsewhere on the internet. I call them math riddles, or comp sci riddles; it depends on the exact content of the challenge. Point is I hate them.

The issue I have is that most of them bear no resemblance to any real world problem faced by the average programmer on the average day. At its core, the issue is that I just don't do those things, and so I have never learned to do those things, and moreover I don't see those as useful things. Anyway, the plan is to "be the change you..." Whatever... You get the idea.

Today's challenge

Use this input file.

Your objective is to tell me the number of unique primes in this file. There are five hundred numbers in total, selected at random. The numbers range from one to 1000.

Both those numbers are kept small on purpose: the idea is not to hand you something that requires a great deal of theoretical knowhow, but to give you something that can be solved in a variety of ways by people of varying skill levels.

I have not decided where or how to post the answer, although I know what it is, and I won't be posting my source code here, because that would defeat the purpose of having the challenge. If you have thoughts on what I ought to do in that regard, feel free to let me know. (I'm really not that difficult to get hold of, I think.)

Edit:

Here is the answer, encoded as Base64: NjcK.