You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 2,7-dimethylphenanthrene;5,8-dimethylquinoxaline;2',7'-dimethylspiro[cyclohexane-1,9'-fluorene];2,7,9,9-tetramethylfluorene .
user
C63H64N2
assistant