COc1cc([N+](=O)[O-])c(S(=O)(=O)[O-])cc1-n1nc(-c2ccccc2)n[n+]1-c1cc(S(=O)(=O)[O-])c([N+](=O)[O-])cc1OC.[Na+]
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?