You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2,3,4,4a,5,6,7,7a-octahydropyrrolo[3,4-b]pyridin-1-yl-(5-ethylthiophen-2-yl)methanone into molecular formula.
user
C14H20N2OS
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