COc1ccc(-c2oc3c(CC=C(C)C)c(O[C@H]4OC(CO)C(O)C(O)C4O)cc(O)c3c(=O)c2O[C@@H]2OC(C)C(O)C(O)C2O)cc1
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?