> MAy I know only the max of count (*) ?

Maybe something like

select first 1 f1, count (*) as quantity
from tbl
where f2="myCondition"
group by f1
order by 2 desc

(I believe this will return the lowest f1 that has the maximum count)

Your questions are more suitable for firebird-support (at)
yahoogroups.com, this list is for specific IBO questions, not general
Firebird SQL questions.

HTH,
Set