You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2,6-dibromo-4-[(Z)-[2-(2-chloro-4-nitrophenyl)-5-oxo-1,3-oxazol-4-ylidene]methyl]phenyl] acetate is the IUPAC name of a molecule. Please give its molecular formula.
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C18H9Br2ClN2O6
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