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-[2-[(6-chloro-3,4-dihydro-2H-thiochromen-4-yl)amino]-2-oxoethyl]-2,4-difluorobenzamide into molecular formula.
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C18H15ClF2N2O2S
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