C[C@]12c3[nH]c4cc(-c5ccco5)ccc4c3CCN1C(=O)[C@@H](CC(=O)NCCc1ccccn1)C[C@@H]2C(=O)N1CCCCC1
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?