You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 1-ethyl-3-(7-oxabicyclo[2.2.1]heptan-2-yl)-2-[(4-pyrrolidin-1-ylsulfonylphenyl)methyl]guanidine into its molecular formula.
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C20H30N4O3S
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