You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (5S)-7-methyl-5-(4-prop-2-ynoxyphenyl)-5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H18N2O3S
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