You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (8S,13S,14R,17S)-17-ethynyl-13-methyl-7,8,12,14,15,16-hexahydro-6H-cyclopenta[a]phenanthrene-3,17-diol into its molecular formula.
user
C20H22O2
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