You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 4-(6-fluoro-2,3,4,9-tetrahydro-1H-carbazole-3-carbonyl)piperazine-1-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H24FN3O3
assistant