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 2-[(2-chloro-4-fluorophenyl)methylsulfanyl]-N-(5-ethyl-6-methyl-4-oxo-2-sulfanylidene-1H-thieno[2,3-d]pyrimidin-3-yl)acetamide is given. What is its corresponding molecular formula?
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C18H17ClFN3O2S3
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