You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 2-[(6aR,9S,10aR)-5-ethenyl-7-ethyl-6,6a,8,9,10,10a-hexahydro-4H-indolo[4,3-fg]quinolin-9-yl]acetamide .
user
C20H25N3O
assistant