You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-(2,6-dimethylpyridin-4-yl)-5,7-dihydrothieno[3,4-d]pyrimidin-4-yl]hydrazine is the IUPAC name of a molecule. Please give its molecular formula.
user
C13H15N5S
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