You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(E)-N-methyl-2-(4-methylphenyl)-N-(5,6,7,8-tetrahydroimidazo[1,2-a]pyridin-6-ylmethyl)ethenesulfonamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H23N3O2S
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