You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[(2,3-dibromo-4,5-dihydroxyphenyl)methyl]-6a-methoxy-3,3a,5,6-tetrahydro-1H-pyrrolo[2,3-d]imidazol-2-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C13H15Br2N3O4
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