You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[[1-(4-methoxyphenyl)sulfonylpiperidin-3-yl]methyl]-5-pyrazin-2-yl-1,2,4-oxadiazole The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H21N5O4S
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