You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4-benzylpiperazin-1-yl)-[(2R)-6-[(4-pyrrolidin-1-ylphenyl)methyl]-6-azaspiro[2.5]octan-2-yl]methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C30H40N4O
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