CC1=C(C(=O)Nc2ccccc2C)C(c2ccc(C3C(C(=O)Nc4ccccc4C)=C(C)NC(C)=C3C(=O)Nc3ccccc3C)cc2)C(C(=O)Nc2ccccc2C)=C(C)N1
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?