You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (2'R,3R,5R,8R,9S,10S,13S,14S,17R)-3-acetyloxy-2'-carbamoyl-10,13-dimethylspiro[1,2,3,4,5,6,7,8,9,11,12,14,15,16-tetradecahydrocyclopenta[a]phenanthrene-17,3'-oxirane]-2'-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C26H39NO6
assistant