Acridine is a heterocyclic aromatic compound obtained from coal tar that is used in the synthesis of dyes. The molecular formula of Acridine is C13H9N, and its ring system is analogous to that of anthracene except that one CH group has been replaced by N. The two most stable resonance structures of Acridine are equivalent to each other, and both contain a pyridine-like structural unit. Write a structural formula for Acridine.