You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(7S)-7-(3-bromophenyl)-5-[4-(difluoromethoxy)phenyl]-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H13BrF2N4O
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