You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[[2-chloro-5-(trifluoromethyl)phenyl]-(3-fluoro-4-methoxyphenyl)methyl]piperidine-2-carboxylic acid by IUPAC nomenclature, provide its molecular formula.
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C21H20ClF4NO3
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