You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named 2-[1-benzothiophen-3-ylmethyl(methyl)amino]-N-[(4S)-3,4-dihydro-2H-chromen-4-yl]acetamide by IUPAC nomenclature, provide its molecular formula.
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C21H22N2O2S
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