COUNTIF number of values associated with a reference

I want to do a count of the number of values associated with a reference

For instance I have

A B C
KO 5
KO 4
KO 7
KO 6
MS 2
MS 7
MS
MS 5

So I want to know there are 4 values for KO and 3 for MS

I'm using AVERAGEIF so can set a range

But need to know how to set a range for COUNTIF

(If it helps my AVERAGEIF forumlar looks a bit like this AVERAGEIF(A1:A8,D1,C1:C8))