You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-[[4-(4-ethoxyphenyl)-5-pyridin-2-yl-1,2,4-triazol-3-yl]sulfanyl]pyridazine-3-carbonitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H15N7OS
assistant