You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1R,3R,3aR,6aS)-1',5-dimethyl-1-(2-methylpropyl)spiro[1,2,3a,6a-tetrahydropyrrolo[3,4-c]pyrrole-3,3'-indole]-2',4,6-trione is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H23N3O3
assistant