5. A deck of 2n cards consists of n red and black cards. These cards are shuffled and then turned over one at a time. Suppose that each time a red card is turned over we win 1 unit if more red cards than black cards have been turned over by that time. (For instance, if n 2 and the result isrbrb, then we would win a total of 2 units.) Find the expected amount that we win.