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 3-(2,5-difluorophenyl)-1-[4-(2-methyl-5-nitrophenyl)sulfonylpiperazin-1-yl]propan-1-one .
user
C20H21F2N3O5S
assistant