You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2-bromo-N-[1-[2-(N-methylanilino)ethylamino]-4-methylsulfanyl-1-oxobutan-2-yl]benzamide into molecular formula.
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C21H26BrN3O2S
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