You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(2R)-1-[4-(4-methoxyphenyl)piperazin-1-yl]-4-methyl-1-oxopentan-2-yl]-3H-isoindol-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C25H31N3O3
assistant