You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 5-[3-[(2,6-dichlorophenyl)methylsulfanyl]phenyl]-4,6-dioxo-7H-thieno[3,2-c]pyridine-3-carboxylic acid is given. What is its corresponding molecular formula?
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C21H13Cl2NO4S2
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