1. (50 points) Prove that the following two circuits are both implementations of the full-adder circuit defined by the truth table in Figure 3.3(a). xi Vi Cs Circuit A Ci+1 2. (50 points) Consider a 1-bit full subtractor circuit which performs 1-bit subtraction with borrow- in. This circuit has three inputs xi, yi, and wi (which is the borrow-in). It computes x -y - w, and store the result in ri and the borrow-out in Wi+1. Please draw the truth tables and write the canonical SOP expressions for the functions r and wii based on Xi, y, and w