You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (3aR,4R,5R,7aR)-N-[(1S)-1-(3,4-difluorophenyl)ethyl]-2,5-dimethyl-1,3-dioxo-3a,4,5,7a-tetrahydroisoindole-4-carboxamide into molecular formula.
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C19H20F2N2O3
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