You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3'-methyl-N-(2-phenylphenyl)-N-spiro[cyclopentane-1,9'-fluorene]-2'-yl-9,9'-spirobi[fluorene]-2'-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C55H41N
assistant