I don't know what you mean. You say there are 20 "extreme points" but also say of the first ten that "monotony is clear as well". What do you mean by "monotony"? That the function is monotone? That's impossible. If the function is monotone, then only its end points can be extreme points.
In any case, just knowing some points on a graph, even if they are "extreme points", tells you nothing about other points, unless you have some precise information about the function.