You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3S,8aR)-3-[4-(2-phenylethynyl)phenyl]-1,2,3,5,6,7,8,8a-octahydroindolizine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H23N
assistant