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Name the molecular formula for the molecule established as ethyl (4R)-4-ethyl-6-[(5-methylsulfanyl-1,3,4-thiadiazol-2-yl)sulfanylmethyl]-2-oxo-3,4-dihydro-1H-pyrimidine-5-carboxylate using the IUPAC nomenclature.
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C13H18N4O3S3
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