You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 1-(6,8-dihydro-5H-imidazo[1,2-a]pyrazin-7-ylmethyl)-1,2,3,4-tetrahydroisoquinoline into its molecular formula.
user
C16H20N4
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