You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(3S)-1-(3-methoxycarbonyl-4,5-dimethylthiophen-2-yl)-2,5-dioxopyrrolidin-3-yl]sulfanylpyridine-3-carboxylic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H16N2O6S2
assistant