You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(4-methyl-2,5-dioxo-4-phenylimidazolidin-1-yl)-N,N-bis(2-methylpropyl)acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H29N3O3
assistant