COUNTIF Any of column A match any of column B

I know how to do this problem in newb-like long form. I would say "=COUNTIF(A:A,B1)" then "=COUNTIF(A:A,B2)", then sum my whole column to find that X number of values in column B matched values in Column A. But that requires a preparation column C to aggregate the information. I'd like to accomplish the same thing in a single cell with one formula.

Thanks for your help!

I'm pretty sure that this is a SUMPRODUCT problem, but I still don't have my mind wrapped around that concept.

Darknation144, what didn't work?

I'm uploading a sample excel spreadsheet showing my expected result with some basic sample data, as well as the long and ineffective way I usually do this.

Just did it with an Array formula {=Count(Match((A1:A10,B1:B10),0))}

Any ideas w/ SUMPRODUCT instead?

Maybe this

=SUMPRODUCT((COUNTIF(B3:B8,A3:A8)*1))

Thanks Cutter, that seems to work