You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-3-(3H-benzo[e]indol-2-yl)-3-oxo-2-[5-(trifluoromethyl)pyridin-2-yl]propanenitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H12F3N3O
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