You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-ethyl-7-[(3-methylpiperazin-1-yl)methyl]-[1,3,4]thiadiazolo[3,2-a]pyrimidin-5-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H19N5OS
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