Can anyone please explain the number and reading order of the percy jackson books? I’m really confused

When I googled it, I've found so many percy jackson titles that I'm really confused.

How many books are there and what's the reading order?

I only want to read the main series by the author and no spinoffs(for example, when I read the LOTR series I read the main books+the hobbit and I skipped The Silmarillion)