You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-(1-methylindol-5-yl)-N-[1-[5-(trifluoromethyl)pyridin-3-yl]pyrrolidin-3-yl]acetamide by IUPAC nomenclature, provide its molecular formula.
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C21H21F3N4O
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