You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 3-amino-2-[2-(3,4-dimethylanilino)-2-oxoethyl]sulfanyl-5-methyl-4-oxothieno[2,3-d]pyrimidine-6-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H22N4O4S2
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