You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 4-cyano-N-[5-[3-(4-fluorophenyl)-1,2,4-oxadiazol-5-yl]-1-methylpyrrolidin-3-yl]benzamide into molecular formula.
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C21H18FN5O2
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