CCC(=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
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?