Design an 8-bit binary subtractor using two 4-bit binary adders in a hierarchical design. The 8-bit binary subtractor should have the following interface: - Input a : first 8-bit operand. - Input b : second 8-bit operand. - Output d:8-bit result. Each 4-bit binary adder is a module with the following interface: - Input a : first 4-bit operand. - Input b : second 4-bit operand. - Input cin:1-bit carry-in signal. - Output s: 4-bit sum. - Output Cout: 1-bit carry-out signal. Draw a circuit diagram for the 8-bit binary subtractor. You do not need to implement the 4-bit adders themselves; just use them as preexisting logic blocks. Be very mindful about your notation when reusing logic blocks and labeling signals