Question 4: [20 Marks] Composing complex logic with basic parts You are to implement a combinational logic that counters the number of 1 bits in a 8-bit binary number. Your logic should take an 8-bit binary input A7A6A0 and output 4 binary bits B3B2B1B0 representing the number of 1s in the input with B3 as the most significant bit (MSB). For example, if A7A6A0=01100111, as it contains 5 bits equal to 1, the output B3B2B1B0 should be 5 in binary format (i.e., 0101). Note that the maximum possible output value is 8 , for which the 4-bit output is sufficiently long. The components you are allowed to use are 1-bit full adders, 1-bit half adders and necessary constants and wires. Please draw the schematic of your design, with a clear indication of each input / output pin and the full and half adders represented with the following symbols (which are the same expect for the number of inputs). Although the number of adders is not limited, you are encouraged to use as few as you can, so that the schematics will be easier to draw and clearer to read