You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(4-bromo-2,5-dimethylpyrazol-3-yl)methyl]-3-ethyl-6-methylpiperazine-2,5-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C13H19BrN4O2
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