You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[(1S,2R,4aS,6R,8aR)-1,3,6-trimethyl-2-propyl-4a,5,6,7,8,8a-hexahydro-2H-naphthalene-1-carbonyl]-4-hydroxypyrrole-2,5-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H29NO4
assistant