O=Cc1ccccc1COC(=O)c1cc(C(=O)OCc2ccccc2C=O)c(C(=O)OCc2ccccc2C=O)cc1C(=O)OCc1ccccc1C=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.