You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-[3-(1-methyl-5-oxo-4-phenyl-1,2,4-triazol-3-yl)piperidine-1-carbonyl]-1H-pyrazin-2-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H20N6O3
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