Design the incoming 4-bit number A₃ A₂ A1 A0 as well as the circuit that can increase / subtract "1" depending on an incoming K select signal, using one bit Full-Adders. The output signal will be S3 S2 S1 S0. When the select signal is K = 0, the value of the incoming number will increase by "1" at the output, while the value of the number will decrease by "1" when K = 1. [You will use four single-bit Full Adders and additional gates]