Multiplexors are not allowed

You need to design a circuit that implements the functions in the following table SO S1Function 0 1 A-B 1 1 A-1 SO and S1 are 1-bit control inputs to select the function of the circuit. Inputs A and B are 4-bit numbers in 2s complement form. The output is also a 4-bit number in 2s complement form. You are allowed to use only one TTL 7483 4-bit adder to implement all the functions. But any number of other components (except the adder) can be used. HINT: Design a combinational logic circuit to modify the input B and the 'carry input" of the adder depending on the control inputs SO and S1