Three:
One to write the light bulb removal program,
one to write the light bulb insertion program, and
one to act as a light bulb administrator to make sure nobody else tries to change the light bulb at the same time.
or
but I'd never seen herbivore [her before]
or
It went back four seconds!
or
None: A `Real Woman' would have plenty of real men around to do it.
or