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 N-[(2S)-1-(cyanomethylamino)-4-methyl-1-oxopentan-2-yl]imidazo[2,1-b][1,3]benzothiazole-2-carboxamide into molecular formula.
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C18H19N5O2S
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