O=C(O)CN(CC(=O)O)Cc1cc2c(-c3ccccc3C(=O)O)c3cc(CN(CC(=O)O)CC(=O)O)c(=O)cc-3oc2cc1O
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?