You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(1R,2S)-2-(4-bromo-3-fluorophenyl)cyclopropyl]-4-oxo-3H-phthalazine-1-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H13BrFN3O2
assistant