You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(3-chloro-4-methylphenyl)methyl]-7-isocyano-4-(4-methylidenepiperidin-1-yl)phthalazin-1-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H22ClN5
assistant