A really really simple one. This shouldn't take more than 2 minutes.

There are three light bulbs in a room on the first floor of a building. Their switches are on the ground floor. The bulbs are not visible while manipulating the switches. You are on the ground floor in front of the switches. All the switches are off. You are free to manipulate them as many times as you want. Then you should go to the first floor and watch the bulbs for as much times as you want. Then without returning to the ground floor you should be able to distinguish the three bulb-switch pairs. Is it possible? How?
Use a little common sense.

If you know the solution, please send it to me. I will post it here along with your name of course :)


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