COc1cc2c(cc1OCCCC(=O)Nc1cc(C(=O)Nc3cc(C(=O)Nc4cc(C(=O)NCCCN(C)C)n(C)c4)n(C)c3)n(C)c1)N=C[C@@H]1CCCN1C2=O
Hydrogen bond acceptor is the chemical compound which contains the lone electron pairs that participate in the hydrogen bond formation. How many hydrogen bond acceptors does the molecule contain?