You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[5-[(6,7-dimethoxy-3,8a-dihydroquinazolin-4-yl)amino]-2,3-dihydroindol-1-yl]-2-(1-methylindazol-3-yl)ethanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C28H28N6O3
assistant