You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-fluoro-3-methyl-N-[1-(2-oxo-1,3-dihydroindol-5-yl)ethyl]-1-benzofuran-2-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H17FN2O3
assistant