You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (1R,2S)-N-[3-(4-benzylpiperidin-1-yl)-3-oxopropyl]-2-methylcyclopropane-1-carboxamide by IUPAC nomenclature, provide its molecular formula.
user
C20H28N2O2
assistant