You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule N-[2-(3-chlorophenyl)-5-oxo-4,6-dihydrothieno[3,4-c]pyrazol-3-yl]-2-(3,4-dimethoxyphenyl)acetamide into molecular formula.
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C21H20ClN3O4S
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