You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-N,9-N-bis(2,5-dimethylphenyl)-4,7,11,11,12,12-hexamethyl-2-N,9-N-bis(4-methylphenyl)-6b,10a-dihydroindeno[2,1-a]fluorene-2,9-diamine by IUPAC nomenclature, provide its molecular formula.
user
C56H58N2
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