COUNTIF multiple criteria?

I am trying to count have many people have working in a 24h period. Each shift is represented by a letter of the alphabet. As an example , lets say there are 3 shifts. Early, Late and night shift.
Early shift = A
Late Shift = B
Night Shift = C
With this, I can count have many people worked in the 24 hour period by using a simple countif code to count each letter A,B,C.

But, I need to count how many full time workers and part time workers there are as a second criteria.
I tried this formula to count full time workers with no success.

=SUMIF(B2:B19,"Full",(COUNTIF(C2:C19,{"A","B","C"}))

I have attached a dummy workbook.
Any help would be appreciated.