N/N=C(\C(=O)Nc1c(Cl)cc([N+](=O)[O-])cc1Cl)C(c1cnc2ccc([N+](=O)[O-])cc2n1)[N+](=O)[O-]
PSA is a commonly used medicinal chemistry metric for the optimization of a drug's ability to permeate cells. Please predict psa of this molecule.