You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R)-1-(2-fluorophenyl)-3-(1,2,3,4-tetrahydroisoquinolin-2-ium-2-yl)pyrrolidine-2,5-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H18FN2O2+
assistant