(c) The inverter is to be adapted such that the output, $V_o$, is floating (i.e. disconnected) when a second input signal, $V_e$, is high: $V_e = V_{DD}$. Assuming that both $V_o$ and $V_e$ are equal to either 0V or $V_{DD}$, design a circuit to achieve this specification, including a description of the states of each transistor and the output voltage for each combination of the input signals. How many additional transistors are required? [5 marks]