You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4R,11aR,11bS)-11b-ethyl-9-[5-hydroxy-6-(hydroxymethyl)-3,4-bis[[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy]oxan-2-yl]oxy-4-methyl-8-methylidene-1,2,3,4a,5,6,6a,7,9,10,11,11a-dodecahydrocyclohepta[a]naphthalene-4-carboxylic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C38H62O18
assistant