COC(=O)[C@@H](O)[C@](O)(CCC(C)C)C(=O)O[C@@H]1C(OC)=C[C@]23CCCN2CCc2cc4c(cc2[C@H]13)OCO4
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.