O=C1CCC[C@@H]2C[C@@]3(C[C@@H]4CCN1[C@@H]42)Nc1cc([N+](=O)[O-])ccc1N=C3NC1CCCCC1
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?