You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (3aR,6aS)-5-ethyl-2-[(1-methylimidazol-2-yl)methyl]-3,3a,6,6a-tetrahydro-1H-pyrrolo[3,4-c]pyrrol-4-one .
user
C13H20N4O
assistant