You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance N-(1H-benzimidazol-2-ylmethyl)-1-[[4-(difluoromethoxy)phenyl]methyl]-5-oxopyrrolidine-2-carboxamide .
user
C21H20F2N4O3
assistant