CCc1c(OC(C)=O)c2c(NC3OC(COC(C)=O)C(OC(C)=O)C(OC(C)=O)C3OC(C)=O)nc(OC)nc2oc1=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.