You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(4-fluorophenyl)-5-(4-methylsulfonylphenyl)-2-[2-oxo-2-[4-(trifluoromethyl)phenyl]ethyl]pyridazin-3-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C26H18F4N2O4S
assistant