You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (17Z)-17-ethylidene-16-hydroxy-2,6,7,8,9,10,11,12,13,14,15,16-dodecahydro-1H-cyclopenta[a]phenanthren-3-one .
user
C19H26O2
assistant