You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-[4-(4-bromo-2-nitrophenyl)piperazin-1-yl]-5-methyl-[1,2,4]triazolo[1,5-a]pyrimidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C16H16BrN7O2
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