You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[1-methyl-2-[2-[4-(4-methylphthalazin-1-yl)piperazin-1-yl]ethyl]benzimidazol-5-yl]propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C26H31N7O
assistant