A 4-bit Johnson counter advances through the sequence D C B A = 0000,1000,0100,0010,0001,0011,0111,1111, and repeats. Show how to implement the Johnson counter using D flip-flops. Fill-in the Remapped FF inputs and K-maps, and show a schematic for the minimized sum of pruducts implementation of the Next State function in the box next to the flip-flops. You may assume that an external reset signal places the counter in state 0000 when asserted. DO NOT make the counter self-starting.