You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-[(2R)-6-azaspiro[2.5]octan-2-yl]-4-ethyl-N-[(1-ethylimidazol-2-yl)methyl]thiadiazole-5-carboxamide into molecular formula.
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C18H26N6OS
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