Pivot Table Counta formula and sum for unhidden cells only
 

I'm working on a pivot table, quite a simple one, about 10 columns, 32 lines.
one of the columns is called "destination country" and included several
countries for eg. France, US, Germany etc...
At the bottom of the table I have set up a COUNTA formula =COUNTA(F8:F40)
which works fine when the entire table is displayed.
When I select only one country to come up on the pivot table eg. USA, the
COUNTA formula will still show the same result as it keeps on included the
hidden and not hidden cells.
Can you please help me finding out a solution so that the COUNTA formula
only shows the number of items that are NOT HIDDEN in the pivot table and
does not take into account HIDDEN lines?

Thank you very much,