O=C(c1ccccc1)c1ccc2[nH]c(-c3c(Cl)c(Cl)c(Cl)c(Cl)c3C(=O)N/N=C/c3ccccc3)nc2c1
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.