You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3,5-dichlorophenyl)methyl 2-(ethylcarbamoyl)-4,6,7,8-tetrahydropyrazolo[1,5-a][1,4]diazepine-5-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H20Cl2N4O3
assistant