You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 2-[4-(3-methoxyphenyl)-2,3-dioxopiperazin-1-yl]-N-[(4-methylphenyl)methyl]acetamide is given. What is its corresponding molecular formula?
user
C21H23N3O4
assistant