You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (3aS,6aR)-5-[methyl-[(5-phenylthiophen-2-yl)methyl]amino]-1,2,3,3a,4,5,6,6a-octahydropentalen-2-ol into its molecular formula.
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C20H25NOS
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