You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (7R,8aR)-7-[(6-methylpyridin-2-yl)methoxy]-2-[(5-methylthiophen-2-yl)methyl]-3,4,6,7,8,8a-hexahydro-1H-pyrrolo[1,2-a]pyrazine into its molecular formula.
user
C20H27N3OS
assistant