You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
8-(4-chlorophenyl)-2-morpholin-4-yl-5,6,7,8-tetrahydro-1H-pyrrolo[3,2-c]azepin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H20ClN3O2
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