You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 3-(3,4-dimethoxyphenyl)-N-[2-(5-fluoro-2-oxo-3H-benzimidazol-1-yl)ethyl]propanamide into its molecular formula.
user
C20H22FN3O4
assistant