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 (3aR,4S,8aS,8bS)-1'-ethyl-2-naphthalen-1-ylspiro[5,6,7,8,8a,8b-hexahydro-3aH-pyrrolo[3,4-a]pyrrolizin-5-ium-4,3'-indole]-1,2',3-trione .
user
C28H26N3O3+
assistant