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 benzyl (2S,5R)-3,3-dimethyl-7-oxo-6-(prop-2-enoylamino)-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate into molecular formula.
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C18H20N2O4S
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