#include <cstdio>#include <cstring>#include <iostream>#include <queue>using namespace std;const int imax_n = 10005;struct node{ int u,v,c; node() { } node(int u,int v,int c):u(u),v(v),c(c) { }}p[2*imax_n];int e;int head[imax_n];int next[imax_n*2];void addEdge(int u,int v,int c){ p[e]=node(u,v,c); next[e]=head[u]; head[u]=e++;}void init(){ memset(head,-1,sizeof(head)); memset(next,-1,sizeof(next)); e=0;}bool vis[imax_n];int dis[imax_n];queue<int >q;int bfs(int s){ int ans=0; int temp_node; while (!q.empty()) q.pop(); memset(vis,0,sizeof(vis)); q.push(s); vis[s]=1; memset(dis,0,sizeof(dis)); while (!q.empty()) { int x=q.front(); q.pop(); if (dis[x]>ans) { ans=dis[x]; temp_node=x; } for (int i=head[x];i+1;i=next[i]) { int y=p[i].v; if (!vis[y]) { vis[y]=1; q.push(y); if (dis[x]+p[i].c>dis[y]) dis[y]=dis[x]+p[i].c; } } } return temp_node;}int main(){ int x,y,c; init(); while (scanf("%d%d%d",&x,&y,&c)!=EOF) { addEdge(x,y,c); addEdge(y,x,c); } x=bfs(1); y=bfs(x); printf("%dn",dis[y]); return 0;}
