COC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)OCC1OC(n2cc(C)c(=O)[nH]c2=O)CC1N=[N+]=[N-]
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?