The DNA has N links; each link has a state in which it is closed with energy 0, and a state in which it is open with energy 'e'. The DNA can only unwind from the left; in other words, the sth link can open if all the links to the left (1, 2, 3, ..... s -1) are open. Using a Metropolis Monte Carlo algorithm, find the average number of open links for e = 0.5kT, e = 2kT, N = 20.