You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(2R,4aS,8aS)-1,2,3,4,4a,5,6,7,8,8a-decahydronaphthalen-2-yl]-5-methylpyrazine-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H23N3O
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