O=C(C[C@H]1C[C@H](C(=O)N2CCOCC2)[C@@]2(CCC3CCCC3)c3[nH]c4cc(-c5ccco5)ccc4c3CCN2C1=O)NCCCn1ccnc1
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?