CCOC(=O)c1c(N2CCCC2)[nH]c(=O)c(C(c2c(O)c(C(=O)OCC)c(N3CCCC3)[nH]c2=O)C(C)C)c1O
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?