You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[4-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]piperazin-1-yl]-(1-methylpyrrolidin-2-yl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H20ClF3N4O
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