Let G be a PRG that stretches the input by two (i.e., G : {0,1}" {0, 1}2n). Consider the following function F and show it is not a PRF. The function F takes an n bit key and a 2n bit input x and is defined as follows: F(x) = = x G(xLXRk) where are the left n bits of x and are the right n bits of x. Do this by constructing a distinguisher and computing P(DF(-) = 1) and P(D() = 1) and showing the difference between the two probabilities is large. f() is a random function.