You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[4-[(6-chloropyridazin-3-yl)sulfamoyl]phenyl]-2-(5-methyl-1,2-benzoxazol-3-yl)acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H16ClN5O4S
assistant