You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(4-chlorophenyl)-6-methyl-4-oxo-N-[2-(4-sulfamoylphenyl)ethyl]pyridazine-3-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H19ClN4O4S
assistant