Byteland has N cities (numbered from to ) and N-1 bidirectional roads. It is guaranteed that there is a route from any city to any other city.

Jeanie is a postal worker who must deliver Kletters to various cities in Byteland. She can start and end her delivery route in any city. Given the destination cities for K letters and the definition of each road in Byteland, find and print the minimum distance Jeanie must travel to deliver all K letters.

Note: The letters can be delivered in any order.

approach for this problem

O(V+E) solution intended