You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-[4-[2-[1-(difluoromethyl)benzimidazol-2-yl]sulfanylacetyl]phenyl]ethyl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H19F2N3O2S
assistant