You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 5,6-dimethyl-3-(3-methylphenyl)-2-[2-oxo-2-(1H-pyrrol-2-yl)ethyl]sulfanylthieno[2,3-d]pyrimidin-4-one is given. What is its corresponding molecular formula?
user
C21H19N3O2S2
assistant