In my basement, at the foot of the stairs, there are three light switches of the typical variety. At the top of those stairs is a single light bulb, also of the typical variety. I know one (and only one) of the three switches will turn the light off and on, but I don't know which one.
While I'm flipping switches, I cannot see the light bulb or any light that might come from it; I have to go upstairs to see what effect my switch-flipping has had. But, I'm also lazy... I'll spend as much time as I think I need downstairs, but once I go upstairs to check the result, I'm done and off to play LotRO.
How should I spend my time flipping switches downstairs so that, when I come upstairs, I know which switch is connected to the light bulb?