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 methyl 2-[[4-(4-chlorophenyl)sulfonylpiperazine-1-carbothioyl]amino]-5-methylthiophene-3-carboxylate is given. What is its corresponding molecular formula?
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C18H20ClN3O4S3
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