O=c1c(C(c2ccc([N+](=O)[O-])cc2)c2c(O)c3ccccc3n(-c3ccccc3)c2=O)c(O)c2ccccc2n1-c1ccccc1
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.