You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 3-diazo-N-(2-ethylphenyl)-6-(4-methylphenyl)sulfonyliminocyclohexa-1,4-diene-1-sulfonamide into its molecular formula.
user
C21H20N4O4S2
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