You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3S,3'R,3'aS,6bS,9R,11bR)-3',6',10,11b-tetramethylspiro[2,3,4,6,6a,6b,7,8,11,11a-decahydro-1H-benzo[a]fluorene-9,2'-3a,4,5,6,7,7a-hexahydro-3H-furo[3,2-b]pyridine]-3-ol by IUPAC nomenclature, provide its molecular formula.
user
C27H41NO2
assistant