You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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ethyl (4S)-6-[[2-(2-chloro-6-fluorophenyl)acetyl]oxymethyl]-2-oxo-4-thiophen-2-yl-3,4-dihydro-1H-pyrimidine-5-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
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C20H18ClFN2O5S
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