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For the molecule named 7-[[2-chloro-3-(trifluoromethyl)phenyl]methyl]-6-methyl-3-pyridin-3-yl-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-8-one by IUPAC nomenclature, provide its molecular formula.
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C19H15ClF3N5O
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