You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6a,9a-dichloro-6-(4-hydroxynaphthalen-1-yl)-8-methyl-1,3,7,9-tetraoxo-3a,4,6,10,10a,10b-hexahydroisoindolo[5,6-e]isoindole-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C26H21Cl2N3O6
assistant