You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-[3-(3-fluoro-4-methylphenyl)propanoyl]azetidin-3-yl]-3a,4,7,7a-tetrahydroisoindole-1,3-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H23FN2O3
assistant