You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(3S)-1-[(1R,4bS,8aR,10aS)-6-cyano-1,4b,8,8,10a-pentamethyl-3,7-dioxo-2,8a,9,10-tetrahydrophenanthren-1-yl]-3,6,6-trimethylnonan-3-yl]-3-ethylurea is the IUPAC name of a molecule. Please give its molecular formula.
user
C35H55N3O3
assistant