You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-[[4-[(1-carboxy-3-oxopropan-2-yl)carbamoyl]-2-methylphenyl]methylsulfamoyl]-2-hydroxybenzoic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H20N2O9S
assistant