[ Examples and counterexamples. Constructions ]

There are five links in a chain, each with three rings.

What is the minimum number of rings that need to be unbuckled and buckled to connect these links into one chain?

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Let's unravel all the rings of one link. The remaining four links will be connected by the three unlinked rings.

## Answer

Three rings.

In this case, the first and last solutions correspond to the scenario where everyone drank only milk or only coffee, while the second solution corresponds to the scenario where they actually drank coffee with milk.

## Answer

5 people.