COC(=O)[C@H]1C[C@H]2[C@@H]3CC[C@H]4C[C@@H](OC)CC[C@]4(C)[C@H]3CC[C@]2(C)[C@@]2(CCCO2)O1
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.