Problem Description
Now that inflation is under control the tax base is fairly stable, and hence the Infernal Revenue Department is desperately seeking more ways of extracting more money from the citizenry. One proposal is to institute a capital gains tax - in particular a tax made on the profit realised by buying and selling shares on the Stock Exchange. This seems to be a safe bet, since most ordinary people are not involved and therefore it will only affect the ``rich'' who can afford to pay. However, the Society of Creative Acountants has heard of these proposals and realise that it could well affect them.
The problem arises from the fact that shares do not have a fixed (or even steadily moving) price, and thus one has to determine which of the entire portfolio were sold. IRD have identified two ways of determining this; called respectively First Bought, First Sold (FBFS) and Last Bought, First Sold (LBFS). T