Exploring Cities

There are $N$ cities in a country and all the cities are connected in form of a tree. There are $K$ special cities that have treasure hidden in them. Chef is interested to explore these special cities, every city has a portal that takes chef to any city he wants and returns him back to the same city. For example, if chef is in the city $i$ and he wants to explore cities $j$ and $k$, on the 1st