You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 2-[(3aS,6aS)-5-(4-methylphenyl)-4,6-dioxo-3a,6a-dihydropyrrolo[3,4-d]triazol-3-yl]-N-(4-ethylphenyl)acetamide into its molecular formula.
user
C21H21N5O3
assistant