You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[3-(4-bromophenyl)sulfonyl-6-oxopyridazin-1-yl]-N-(3,5-dimethylphenyl)acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H18BrN3O4S
assistant