Problem with countif, index and sequence

Dear all,
I have a problem when using countif on the result of index with sequence. As the attachment, I would like to count how many A1 in the first ten largest of sum.
Firstly, I take successfully first ten largest of sum by using: index(sort(A1:C31,3,-1),sequence(10),2) (in E2) but when I put this formula into countif to count how many A1 in the result, it returns error in value: countif(index(sort(A1:C31,3,-1),sequence(10),2),"A1") (in F2).
The problem is from sequence in index but I don't know how to solve it.
Any help would be greatly appreciated.
Thank you.

Phung