O=C1C=C2CC[C@H]3[C@@H]4CC[C@H](OC(=O)c5cccc6cc7ccccc7nc56)[C@H]4CC[C@@H]3[C@H]2CC1
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?