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-[(5-ethoxy-2-methyl-2,3-dihydro-1-benzofuran-6-yl)methyl]-2-methyl-3-(2-pyridin-2-ylethyl)guanidine into molecular formula.
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C21H28N4O2
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