You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named (5S,8aR)-5-(5-methoxy-3-methyl-5-oxopent-3-enyl)-5,6,8a-trimethyl-3,4,4a,6,7,8-hexahydronaphthalene-1-carboxylic acid is given. What is its corresponding molecular formula?
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C21H32O4
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