You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 4-[2-[4-[[2-(4-bromo-5-methylpyrazol-1-yl)acetyl]amino]-3-methylpyrazol-1-yl]propanoyl]piperazine-1-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28BrN7O4
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