One. You don't believe me do you? I've got photos! See that big blob? Well, just squint your eyes a bit. . . .
or
or
Someone stepped on its mouse.
or
They turn from notating nuclear spins to notating unclear puns.
or
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