#include<iostream> #include<cstdio> #include<cstdlib> #include<algorithm> #include<cstring> #include<cmath> #define ll long long using namespace std; inline int read() { int x=0,f=1; char ch=getchar(); while(!isdigit(ch)){if(ch=='-')f=-f;ch=getchar();} while(isdigit(ch)){x=10*x+ch-'0';ch=getchar();} return x*f; } int n,first[10010],to[10010],next[10010],val[10010],cnt; inline void add(int u,int v,int w) { to[++cnt]=v; next[cnt]=first[u]; first[u]=cnt; val[cnt]=w; } int dp[10010][2],depth1[10010],depth2[10010]; int dfs1(int x,int fa) { for(int i=first[x];i;i=next[i]) { int v=to[i]; if(v==fa)continue; dp[x][0]=max(dfs(v)+val[i],dp[x][0]); } return dp[x][0]; } int vis[10010]; int dfs2(int x,int fav) { int max1=0,max2=0; int flag1,flag2; if(vis[x])continue; for(int i=first[x];i;i=next[i]) { int v=to[i]; if(vis[v])continue; int tmp=dp[v][0]+val[i]; if(tmp>max1) { max2=max1; max1=tmp; flag2=flag1; flag1=v; } if(tmp==max1 || tmp>max2) { max2=max1; max1=tmp; flag2=v; } } if(x!=1) { int tmp=dp[x][1]; int v=-2; if(tmp>max1) { max2=max1; max1=tmp; flag2=flag1; flag1=v; } if(tmp==max1 || tmp>max2) { max2=max1; max1=tmp; flag2=v; } } for(int i=first[x];i;i=next[i]) { int v=to[i]; if(v==flag1) dp[x][1]=max2+val[i]; else dp[x][1]=max1+val[i]; dfs2(v,val[i]); } } int main() { n=read(); for(int i=1;i<n;i++) { int u,v,w; u=read();v=read();w=read(); add(u,v,w);add(v,u,w); } dfs1(1,-1); }