You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 5-[4-(1H-imidazol-2-ylmethyl)piperidine-1-carbonyl]-3,3-dimethyl-1H-indol-2-one by IUPAC nomenclature, provide its molecular formula.
user
C20H24N4O2
assistant