[{"sectionTitle":"题目描述","type":"Text","text":"给出 $n$ 个点的一棵树，多次询问两点之间的最短距离。\r\n\r\n注意：边是双向的。","subType":"markdown"},{"sectionTitle":"输入格式","type":"Text","text":"第一行为两个整数 $n$ 和 $m$。$n$ 表示点数，$m$ 表示询问次数；\r\n\r\n下来 $n-1$ 行，每行三个整数 $x ,y, k$，表示点 $x$ 和点 $y$ 之间存在一条边长度为 $k$；\r\n\r\n再接下来 $m$ 行，每行两个整数 $x, y$，表示询问点 $x$ 到点 $y$ 的最短距离。","subType":"markdown"},{"sectionTitle":"输出格式","type":"Text","text":"输出 $m$ 行。对于每次询问，输出一行。","subType":"markdown"},{"sectionTitle":"样例 1","type":"Sample","text":"","subType":"markdown","payload":["2 2\n1 2 100\n1 2\n2 1","100\n100"]},{"sectionTitle":"样例 2","type":"Sample","text":"","subType":"markdown","payload":["3 2\n1 2 10\n3 1 15\n1 2\n3 2","10\n25"]},{"sectionTitle":"数据范围与提示","type":"Text","text":"对于全部数据，$2\\le n\\le 10^4,1\\le m\\le 2\\times 10^4,0\\lt k\\le 100,1\\le x,y\\le n$。","subType":"markdown"}]