You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-(4-bromophenyl)sulfonylpiperazin-1-yl]-N-(2,4-difluorophenyl)acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H18BrF2N3O3S
assistant