You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2,5-dimethyl-N-[2-[4-(3-methylphenyl)piperazin-1-yl]-2-oxoethyl]furan-3-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H25N3O3
assistant