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system
Name the molecular formula for the molecule established as 2-[1-[(2-chloro-4-fluorophenyl)methyl]-3,5-dimethylpyrazol-4-yl]-3a,4,5,6,7,7a-hexahydro-4,7-epoxyisoindole-1,3-dione using the IUPAC nomenclature.
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C20H19ClFN3O3
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