You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R,3S,5R)-2-(2,5-difluorophenyl)-5-(5-methylsulfonyl-2,3,3a,4,6,6a-hexahydropyrrolo[3,4-b]pyrrol-1-yl)oxan-3-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H25F2N3O3S
assistant