You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-N-(3-chloro-4-fluorophenyl)-2-[3-(4-methylphenyl)-1,2,4-oxadiazol-5-yl]piperidine-1-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20ClFN4O2
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