You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (2E)-2-[(1R,4aS,4bR,7S,8aR,10S,10aS)-7,10-dihydroxy-1,4b,8,8-tetramethyl-3,4,4a,5,6,7,8a,9,10,10a-decahydro-1H-phenanthren-2-ylidene]acetic acid into molecular formula.
user
C20H32O4
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