CF845G.Shortest Path Problem?

You are given an undirected graph with weighted edges. The length of some path between two vertices is the bitwise xor of weights of all edges belonging to this path (if some edge is traversed more than once, then it is included in bitwise xor the same number of times). You have to find the minimum length of path between vertex 1 and vertex n.

Note that graph can contain multiple edges and loops. It is guaranteed that the graph is connected.

给你一个带权无向图。路径的长度定义为该路径上所有边的权重的按位异或值（若某条边被经过多次，则该边的权重在按位异或运算中也参与相应次数）。你需要求出顶点 1 与顶点 $n$ 之间路径的最小长度。

注意：图中可能包含重边和自环。题目保证图是连通的。

The first line contains two numbers n and m (1 ≤ n ≤ 100000, n - 1 ≤ m ≤ 100000) — the number of vertices and the number of edges, respectively.

Then m lines follow, each line containing three integer numbers x, y and w (1 ≤ x, y ≤ n, 0 ≤ w ≤ 108). These numbers denote an edge that connects vertices x and y and has weight w.

第一行包含两个整数 $n$ 和 $m$（$1 ≤ n ≤ 100000$，$n - 1 ≤ m ≤ 100000$），分别表示顶点数和边数。

接下来有 $m$ 行，每行包含三个整数 $x$、$y$ 和 $w$（$1 ≤ x, y ≤ n$，$0 ≤ w ≤ 10^8$）。这表示一条连接顶点 $x$ 和 $y$、权重为 $w$ 的边。

Print one number — the minimum length of path between vertices 1 and n.

输出一个数字——顶点 1 与顶点 $n$ 之间路径的最小长度。