#include<iostream>
#include<vector>
#include<algorithm>
#include<climits>
struct edge{
int n,w;
};
static std::vector<std::vector<edge>> ad;
static std::vector<int> parw;
static std::vector<int> f,g;
// f[i]: max value of subtree rooted at i,
// g[i] = ~ but also include edge from i to parent
static void dfs(int i){
int sg=0;
int m1=INT_MIN,m2=INT_MIN; // maximum gain values in score when replace g by f
// and pair that edge (to node i) where m1 >= m2
for(edge e:ad[i]){
int j=e.n,w=e.w;
// par[j]=i;
parw[j]=e.w;
ad[j].erase(
std::find_if(begin(ad[j]),end(ad[j]),[i](edge e){
return e.n==i;
}));
dfs(j);
sg+=g[j];
int m=f[j]-g[j]+w;
m2=std::max(m2,m);
if(m2>m1)std::swap(m1,m2);
}
f[i]=sg;
if(m2!=INT_MIN)
f[i]=std::max(sg,m1+m2+sg);
g[i]=f[i];
if(m1!=INT_MIN)
g[i]=std::max(g[i],sg+m1+parw[i]);
}
int main(){
int n;std::cin>>n;
ad.resize(n);
for(int _=n-1;_--;){
int a,b,w;std::cin>>a>>b>>w;--a;--b;
ad[a].push_back({b,w});
ad[b].push_back({a,w});
}
// par.resize(n);
parw.resize(n);
f.resize(n);
g.resize(n);
dfs(0);
std::cout<<f[0]<<'\n';
}
