B'You are given an undirected tree consisting of n vertices. An undirected tree is a connected undirected graph with n - 1 edges. Your task is to add the minimum number of edges in such a way that the length of the shortest path from the vertex 1 to any other vertex is at most 2 . Note that you are not allowed to add loops and multiple edges. The first line contains one integer n ( 2 <= n <= 2 cdot 10^5 ) -- the number of vertices in the tree. The following n - 1 lines contain edges: edge i is given as a pair of vertices u_i, v_i ( 1 <= u_i, v_i <= n ). It is guaranteed that the given edges form a tree. It is guaranteed that there are no loops and multiple edges in the given edges. Print a single integer -- the minimum number of edges you have to add in order to make the shortest distance from the vertex 1 to any other vertex at most 2 . Note that you are not allowed to add loops and multiple edges. The tree corresponding to the first example: The answer is 2 , some of the possible answers are the following: [(1, 5), (1, 6)] , [(1, 4), (1, 7)] , [(1, 6), (1, 7)] . The tree corresponding to the second example: The answer is 0 . The tree corresponding to the third example: The answer is 1 , only one possible way to reach it is to add the edge (1, 3) . '...