CN1C[C@H](C(=O)N[C@]2(C)O[C@@]3(O)[C@H]4CCCN4C(=O)[C@H](Cc4ccccc4)N3C2=O)C[C@H]2c3cccc4[nH]cc(c34)C[C@@H]21
A lower number of pka indicates that the acid dissociates more entirely in water. What is pka of the molecule?