You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (E)-N-[[3-fluoro-4-(2-methylimidazol-1-yl)phenyl]methyl]-3-(2-methoxyphenyl)prop-2-enamide into its molecular formula.
user
C21H20FN3O2
assistant