Stringer Bell sells two products, red candy for $4 and yellow candy for $5. In a typical hour, 5 customers will buy only red candy and 4 customers buy only yellow candy, but there are 2 people who buy both. After asking around, Stringer Bell learns that the red-candy buyers would also buy yellow candy if it were to cost $2, and yellow-candy buyers would also buy red candy if they were sold for $2. Stringer Bell considers selling red and yellow candy together in a bundle, in addition to selling them separately at the original prices. What is the optimal price of the bundle