count distinct values in spreadsheet

Question

I have a Google spreadsheet with a column that looks like this:

City
----
London
Paris
London
Berlin
Rome
Paris

I want to count the appeara

Answer 1

=UNIQUE({filter(Core!L8:L27,isblank(Core!L8:L27)=false),query(ArrayFormula(countif(Core!L8:L27,Core!L8:L27)),"select Col1 where Col1 <> 0")})

Core!L8:L27 = list