INTRODUCING "NAND GATES"
The NAND Gate is the opposite of an AND Gate. If a either lead A or lead B is in a state of 1, C will be in a state of 1. If A and B is in a state of 1, C will be in a state of 0. Only if both A and B are in a state of 0 is C in a state of 1.

Like the NOR Gate, the NAND Gate is Universal. This means that like the NOR Gate, you can use NAND Gates to make all of the decisions on the right.Next

To make it possible to have either one color or the other drop the same box, you add an OR Gate.