You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(E)-N-[1-(2,3-dihydro-1-benzofuran-5-yl)ethyl]-3-[4-(trifluoromethyl)phenyl]prop-2-enamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H18F3NO2
assistant