You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 2,4,5,6-tetrabromo-3-methylsulfanyl-1-(4,5,6-tribromo-2-methylsulfanyl-1H-indol-3-yl)indole .
user
C18H9Br7N2S2
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