O=[N+]([O-])c1ccc2c(c1)/C(=N/N=C1c3ccccc3Cc3ccccc31)c1cc([N+](=O)[O-])cc([N+](=O)[O-])c1-2
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?