of this P of n is N squared or in cubed something like that so this is what we mean by easy most of the things that you see when you're learning our than they're easy sorting easy so this problem was articulated in 1970s by Steve cook and the carp and also in the Soviet Union by leonid 11 okay so the rather than going into definitions and things like this I will just give you an illustration of this and probably the best illustration of the difference between P and NP is the problem of factoring numbers so suppose I give you