You are given an unweighted, undirected tree. Write a program to find a vertex set of minimum size in this tree such that each edge has as least one of its end-points in that set. \includegraphics{https://static.e-olymp.com/content/b9/b91b096d8150f877ba7b7772586cd6954df650a2.gif} \InputFile The first line contains one integer $n~(0 < n \le 10^5)$ --- number of nodes in the tree. Next $n - 1$ lines contain $n - 1$ edges of that tree. Each line contains a pair $(u, v)$ means there is an edge between node $u$ and node $v~(1 \le u, v \le n)$. \OutputFile Print number of nodes in the satisfied vertex set on one line.