Nc1c([N+](=O)[O-])cc([N+](=O)[O-])c(-c2nnc(-c3c([N+](=O)[O-])cc([N+](=O)[O-])c(N)c3[N+](=O)[O-])s2)c1[N+](=O)[O-]
Hydrogen bond acceptor: The atom, ion, or molecule component of a hydrogen bond which does not supply the bridging (shared) hydrogen atom. How many hydrogen bond acceptors does the molecule have?