You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (4R,6S,6aR,9S)-2-methoxy-3,6,9-trimethyl-4-(2-methylprop-1-enyl)-5,6,6a,7,8,9-hexahydro-4H-phenalen-1-ol into molecular formula.
user
C21H30O2
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