You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2S,4aR,7S,8aR)-7-methyl-4-methylidene-2-phenyl-2,3,4a,5,6,7,8,8a-octahydrochromene by IUPAC nomenclature, provide its molecular formula.
user
C17H22O
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