O=C1[C@H]2[C@@H]3c4ccccc4[C@@H]([C@@H]2C(=O)N1c1ccc(OCc2ccccc2)cc1)[n+]1ccccc13
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?