You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule N-(3-chloro-4-fluorophenyl)-N-[2-[(2R)-2-methyl-2,3-dihydroindol-1-yl]-2-oxoethyl]methanesulfonamide into molecular formula.
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C18H18ClFN2O3S
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