You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[3-(1-benzyl-1,2,3,6-tetrahydropyridin-1-ium-5-yl)indol-1-yl]pent-4-en-1-one;chloride is the IUPAC name of a molecule. Please give its molecular formula.
user
C25H27ClN2O
assistant