You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-cyclopropyl-N-[2-[4-(4-methoxyphenyl)piperazin-1-yl]-2-oxoethyl]-2-oxoacetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H23N3O4
assistant