keytruda is exciting, people are excited about it. announced today that you are expanding that pipeline. how are you looking at that drug and how does the pricing cost come into that in terms of paying for the expensive drugs together. >> as you just said. it is a very exciting field. harnessing the body to fight the tumors. and we are still in the beginning chapters and we are still understanding monotherapy which is across many tumor types. but we think ultimately for many patients combinations are necessary and we're exploring 80 combinations through partners p partnerships, et cetera. with respect to pricing. i think we'll have to think rationally about pricing. because you can't stack drug on drug and expect that patients could pay for them. so we have to think about how we discern the value that each component brings and how we could make them affordable and accessible. >> so you have a lot of good things coming this year. alzheimer's, cholesterol, cancer, what is the most exciting thing in your pipeline right now. >> that is ha