You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[[5-(oxolan-2-ylmethylamino)-1,3,4-thiadiazol-2-yl]sulfanylmethyl]pyrido[1,2-a]pyrimidin-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H17N5O2S2
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