Data worksheet tracking trades from one person to another:

+------+----+-----+ | From | To | Amt | +------+----+-----+ | A | B | 10 | +------+----+-----+ | B | C | 5 | +------+----+-----+ | A | C | 3 | +------+----+-----+ | C | B | 2 | +------+----+-----+

How do I create a pivot table (using Calculated Items, Calculated Fields, etc.) that would look like the following?

+--------+-----+ | Person | Net | +--------+-----+ | A | -13 | +--------+-----+ | B | 7 | +--------+-----+ | C | 6 | +--------+-----+ | Total | 0 | +--------+-----+