You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(8aR)-7-(1H-indol-3-ylmethyl)-2-[(4-methoxyphenyl)methyl]-5,6,8,8a-tetrahydro-1H-imidazo[1,5-a]pyrazin-3-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C23H26N4O2
assistant