You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 1-[(4aS,8aS)-4a-hydroxy-7-(2-methoxyacetyl)-3,4,5,6,8,8a-hexahydro-1H-2,7-naphthyridin-2-yl]-3-thiophen-3-ylpropan-1-one into molecular formula.
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C18H26N2O4S
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