KöMaL 2017 C1441
A coffee shop serves coffee specials made from various ingredients. For any item selected from the menu there exist exactly three others that each have some ingredient in common with the selected item. If two menu items have no ingredient in common then there exists a third one that has an ingredient in common with each of the two. What is the maximum possible number of items on the menu of cofee specials?
Official text KöMaL. Quoted with source.
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