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Puzzle:

There are 100 doors in a long hallway. They are all closed. The first time you walk by each door, you open it. The second time around, you close every second door (since they are all opened). On the third pass you stop at every third door and ...

You must print the lyric of the song as follows:

``` 99 bottles of beer on the wall, 99 bottles of beer. Take one down and pass it around, 98 bottles of beer on the wall. 98 bottles of beer on the wall, 98 ...

There is a pile of twelve coins, all of equal size. Eleven are of equal weight. One is of a different weight. In three weighings find the unequal coin and determine if it is heavier or ...