You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[[2-[(3R,4R)-3-amino-4-fluoropiperidin-1-yl]-4-methoxybenzimidazol-1-yl]methyl]benzonitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H22FN5O
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