You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule (3R,7R)-13-thia-1-azapentacyclo[10.7.1.03,7.08,20.014,19]icosa-5,8(20),9,11,14,16,18-heptaene ?
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C18H15NS
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