You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(methylsulfonylmethyl)-N-[4-(2-oxopyrrolidin-1-yl)phenyl]-1-benzofuran-2-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H20N2O5S
assistant