A traffic light controller receives a $4-$bit input that changes every $5$ seconds. The input sequence is a simple

counter that counts from binary $0$ to binary $15$ and then starts again from binary $0.$ These signals go to $4$ outputs,

NSH$,$ NSL$,$ EWH, EWL. The first two outputs NSH and NSL respectively represent the high and low bits that

are fed to the lamps that face in the North$-$south direction. The other two outputs EWH and EWL respectively

represent the high and low bits that are fed to the lamps that face in the East$-$West direction. The following table

indicates how setting the high and low bits determines the color of the lamp: