You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3Z)-5,7-dibromo-3-[(2,3-dihydroxyphenyl)methylidene]-4-methyl-1H-indol-2-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C16H11Br2NO3
assistant