You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(4aR,8aS)-1-benzyl-2,3,4,4a,5,7,8,8a-octahydro-1,6-naphthyridin-6-yl]-(thiadiazol-5-yl)methanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H22N4OS
assistant