O=[N+]([O-])c1ccc2nc(/C(=N/Nc3ccccc3)C(O)c3ccc(C(O)/C(=N\Nc4ccccc4)c4nc5ccc([N+](=O)[O-])cc5nc4O)cc3)cnc2c1
Hydrogen bond acceptor is the chemical compound which contains the lone electron pairs that participate in the hydrogen bond formation. This compound should contain a more electronegative atom (more electronegative than hydrogen) with lone electron pairs. Then it can attract protons from a donor. Moreover, the electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?