You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule spiro[4,4a-dihydrofluorene-9,9'-fluorene]-2-yl(spiro[4b,8a-dihydrofluorene-9,9'-fluorene]-2-yl)methanone ?
user
C51H34O
assistant