You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[4-(2-ethylphenyl)-4-methylpiperidin-1-yl]-2-[[phenyl(pyridin-2-yl)methyl]amino]ethanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C28H33N3O
assistant