Only one, but he'll just hire a ghostwriter to do it for him.
Two. One to identify that the lightbulb has indeed burned out, and one to call the maintenence man to change the lightbulb.
Trick question. Protestors don't change anything.
I want that job. I could really screw with some people.
Two. One to screw it in and one to take credit for it.
Hire a cunning linguist.
The Whittle Business *badum ching*