Am I doing myself a disservice by reading only the first and third of Kant's Critiques?

My university bookstore really only sells those two. I have never ever seen the second Critique in stock. I am not a formal student of philosophy (I study math and statistics) but I bought the third Critique last year, and have been slowly making my way through it. I have just bought the first one - Critique of Pure Reason -today. Both are the blue Cambridge books.

I have seen one University in America have a course that requires only the first and third as readings. So with that in mind, what am I missing out on by ignoring the second Critique?