You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (2S,4S,6S,12bR)-2-(2-acetamidoethylamino)-4-phenyl-1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a]quinolizine-6-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C27H32N4O3
assistant