A newsstand manager must decide how many daily papers to stock. Past experience has shown that demand can be approximated by a normal distribution with a mean of 400 papers and a standard deviation of 80 papers. The manager pays 30 cents for each paper, sells it for 50 cents, and any papers not sold are picked up by the distributor, with the manager receiving 5 cents for each of them. If the manager wants to maximize his expected profit, how many newspapers should be stocked?