You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name N-(2-acetylphenyl)-2-[4-(3,4-dichlorophenyl)-4-methyl-2,5-dioxoimidazolidin-1-yl]acetamide ?
user
C20H17Cl2N3O4
assistant