You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[(4-chlorophenyl)methyl]-2-[1-[3-(4-methoxyphenyl)propyl]azepan-4-yl]phthalazin-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C31H34ClN3O2
assistant