You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-(3-chloro-4-methylphenyl)-N-[2-(4-formylpiperazin-1-yl)-2-oxoethyl]benzenesulfonamide by IUPAC nomenclature, provide its molecular formula.
user
C20H22ClN3O4S
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