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system
Name the molecular formula for the molecule established as N-[2-[(2S,3S)-1-ethyl-2-methylpyrrolidin-3-yl]thieno[2,3-b]pyridin-4-yl]-4-fluoro-1,3-benzothiazol-5-amine using the IUPAC nomenclature.
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C21H21FN4S2
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