COC(=O)C(=O)C(C(=O)C(=O)Nc1ccc(OC)cc1[N+](=O)[O-])c1nc2ccc([N+](=O)[O-])cc2nc1O
Hydrogen bond acceptor is the chemical compound which contains the lone electron pairs that participate in the hydrogen bond formation. How many hydrogen bond acceptors does the molecule contain?