You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R,5R,8R,9S,10S,13S,14S,16R,17R)-16-bromo-10,13-dimethyl-2,3,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthrene-3,17-diol is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H31BrO2
assistant