You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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2-[[3-(2-chlorophenyl)-1,2,4-oxadiazol-5-yl]oxy]-N-[5-methyl-2-(4-methylphenyl)pyrazol-3-yl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
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C21H18ClN5O3
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