Description: You are given a tree, consisting of $$$n$$$ vertices. Each edge has an integer value written on it. Let $$$f(v, u)$$$ be the number of values that appear exactly once on the edges of a simple path between vertices $$$v$$$ and $$$u$$$. Calculate the sum of $$$f(v, u)$$$ over all pairs of vertices $$$v$$$ and $$$u$$$ such that $$$1 \le v < u \le n$$$. Input Format: The first line contains a single integer $$$n$$$ ($$$2 \le n \le 5 \cdot 10^5$$$) — the number of vertices in the tree. Each of the next $$$n-1$$$ lines contains three integers $$$v, u$$$ and $$$x$$$ ($$$1 \le v, u, x \le n$$$) — the description of an edge: the vertices it connects and the value written on it. The given edges form a tree. Output Format: Print a single integer — the sum of $$$f(v, u)$$$ over all pairs of vertices $$$v$$$ and $$$u$$$ such that $$$v < u$$$. Note: None