You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-(3,4-dimethoxyphenyl)ethyl]-N-methyl-3-[(4-oxo-5,6,7,8-tetrahydro-3H-phthalazin-1-yl)methyl]benzamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C27H31N3O4
assistant