Please design and draw the schematic of a combinational circuit that compares two 4-bit unsigned numbers A and B to see whether they are equal. The circuit has one output X, so that X = 1 if A = B and X = 0 if A 6= B. You can use full-adders and not gates only.

(Hint: There is an XOR gate in the full adders. If the inputs of the full adder are different, and the carry-in is 1, the sum output is 0. We can compare the least significant pair first, then propagate the comparison result to the second least significant pair, and so on and so foth.)