You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name [3-(7-isocyano-3,4-dihydro-1H-isothiochromen-4-yl)imidazol-4-yl]-pyrrolidin-1-ylmethanone into its molecular formula.
user
C18H18N4OS
assistant