Counting non-duplicates using countifs() with other criteria - how?

I am currently using a countifs() function to count from a large dataset only certain rows based on criteria X, Y, and Z (i.e. countifs(range_a,X1,range_b,Y1,range_c,Z1)
However, in range_a, there are a lot of duplicates, and I'd like to avoid counting those.

How do I write the formula such that I count properly based on criteria X1, Y1, and Z1, while still avoiding counting duplicates in range_a?