You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-oxo-N-[[1-(2-phenylethyl)piperidin-4-yl]methyl]-1-prop-2-enylpyrrolidine-3-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H31N3O2
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