You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3S,4aS,8aR)-N,N-dimethyl-6-[2-(2-oxopyridin-1-yl)acetyl]-2,3,4,4a,5,7,8,8a-octahydropyrano[3,2-c]pyridine-3-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H25N3O4
assistant