You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
10-tert-butyl-7-ethyl-1,3,8-trimethyl-6-prop-1-enyl-6,7-dihydropyrazino[2,1-a]isoquinolin-5-ium is the IUPAC name of a molecule. Please give its molecular formula.
user
C24H33N2+
assistant