CC(=O)OCC1OC(n2c(=S)n(-c3ccc([N+](=O)[O-])cc3)c(=O)c3ccccc32)C(OC(C)=O)C(OC(C)=O)C1OC(C)=O
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?