You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(5-bromo-2-fluorophenyl)-4,5,7,8-tetrahydro-3aH-oxepino[4,5-c]pyrazol-3-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C13H12BrFN2O2
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