O=C(NN1C(=O)C(Cl)C1c1ccc(Cl)cc1)c1c(Cl)c(Cl)c(Cl)c(Cl)c1-c1nc2ccccc2[nH]1
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?