You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 2-[(E)-[[2-[4-(4-bromophenyl)sulfonylpiperazin-1-ium-1-yl]acetyl]hydrazinylidene]methyl]phenolate is given. What is its corresponding molecular formula?
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C19H21BrN4O4S
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