You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (2S,3aS,8aS)-3a-methyl-2-phenyl-1-(2-pyrazol-1-ylacetyl)-3,4,6,7,8,8a-hexahydro-2H-pyrrolo[3,2-b]azepin-5-one .
user
C20H24N4O2
assistant