COC(=O)C1OC(=O)C2OC23[C@@]1(C)CCC1[C@@]3(C)C(O)CC2C(C)(C)C(OC(C)=O)CC(OC(C)=O)[C@]21C
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?