In the Counting 2 handout's problem section number 2, it says n/2<=k<=n. Is this k fixed for the function f(X) or does the second condition mean n/2<=f(x)<=n for all x in X? (also, why are there absolute bars? if f:X->X and all elements of X are positive, why are absolute values necessary? Unless it actually means the size of the range of f(x) is equal to k?)