C/C=C/C(=O)Nc1cccc(C2=NOC3(C2)C[C@@H](C(N)=O)N(C(=O)c2cc([N+](=O)[O-])cc([N+](=O)[O-])c2)C3)c1
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?