You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3a-(4-bromophenyl)-7,8b-dihydroxy-6,8-dimethoxy-N-oxo-3-phenyl-2,3-dihydro-1H-cyclopenta[b][1]benzofuran-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C26H22BrNO7
assistant