You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (5S,8R,9R,10S,13R,14S,17S)-17-ethyl-13-methyl-2,4,5,6,7,8,9,10,11,12,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-one into molecular formula.
user
C20H32O
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