You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[1-[(5-methyl-1H-imidazol-4-yl)methyl]-6,6-dioxo-2,3,4a,5,7,7a-hexahydrothieno[3,4-b]pyrazin-4-yl]-(6-methylpyridin-2-yl)methanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H23N5O3S
assistant