You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 3-(3-chlorophenyl)-4-oxo-2-piperazin-1-yl-5H-pyrazolo[1,5-a]pyrazine-6-carboxylate;hydrochloride is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H21Cl2N5O3
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