You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3aS,8aS,8bS)-2-(2,6-dimethylphenyl)spiro[3a,6,7,8,8a,8b-hexahydropyrrolo[3,4-a]pyrrolizine-4,2'-indene]-1,1',3,3'-tetrone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C25H22N2O4
assistant