You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
8-benzhydryl-7-methyl-5-[[4-(trifluoromethyl)phenyl]methyl]-2,5,8-triazaspiro[3.5]nonane-6,9-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C28H26F3N3O2
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