CC(C)(C)OC(=O)NCCCC[C@H](NC(=O)C1CCN(C(=O)OC(C)(C)C)CC1)c1nnc(CNC(=O)OC(C)(C)C)o1
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?