You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance (8R,9S,13S,14S,17S)-6-ethyl-13-methyl-8,9,11,12,14,15,16,17-octahydro-7H-cyclopenta[a]phenanthrene-3,6,17-triol .
user
C20H28O3
assistant