N/N=C(\C(=O)Nc1c(Cl)cc([N+](=O)[O-])cc1Cl)C(c1cnc2ccc([N+](=O)[O-])cc2n1)[N+](=O)[O-]
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?