#include<bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
#define ykh mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define __lg(x) 63-__builtin_clzll(x)
#define pow2(x) (1LL<<x)
void __print(int x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
#ifdef local
void CHECK();
void setio(){
freopen("/Users/iantsai/cpp/input.txt","r",stdin);
freopen("/Users/iantsai/cpp/output.txt","w",stdout);
}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
void setio(){}
#define debug(x...)
#endif
#define TOI_is_so_de ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);setio();
int n;
const int mxn = 2e5+5;
const int inf = -1e18;
vector<pii>adj[mxn];
int dp[mxn], ans = 0;
pii dp2[mxn][2];
void dfs(int v,int pa){
int sum = 0;
for(auto [u, d] : adj[v]){
if(u == pa) continue;
dfs(u, v);
dp[v] += max(dp[u], dp2[u][0].F+d);
}
for(auto [u, d] : adj[v]){
if(u == pa) continue;
pii p = {dp[v]-max(dp[u], dp2[u][0].F+d)+d+dp[u], u};
auto &x=dp2[v];
if(p.F >= x[0].F){
x[1] = x[0];
x[0] = p;
}
else if(p.F > x[1].F){
x[1] = p;
}
}
if(sz(adj[v])==1 and pa!=v){
dp2[v][0]={inf,inf};
dp2[v][1]={inf,inf};
}
}
void cal(int v,int pa){
chmax(ans, dp[v]);
for(auto [u, d] : adj[v]){
if(u == pa) continue;
auto p = dp2[v];
auto x = dp[v];
dp[v] -= max(dp[u], dp2[u][0].F+d);
auto p1 = dp2[v][0];
if(p1.S == u) p1 = dp2[v][1];
p1.F -= max(dp[u], dp2[u][0].F+d);
dp[u] += max(dp[v], p1.F+d);
dp2[u][0].F += max(dp[v], p1.F+d);
dp2[u][1].F += max(dp[v], p1.F+d);
pii p2 = {dp[u]-max(dp[v], p1.F+d)+d+dp[v], v};
if(p2.F >= dp2[u][0].F){
dp2[u][1] = dp2[u][0];
dp2[u][0] = p2;
}
else if(p2.F >= dp2[u][1].F){
dp2[u][1] = p2;
}
cal(u,v);
dp[v] = x;
dp2[v][0]=p[0];
dp2[v][1]=p[1];
}
}
signed main(){
TOI_is_so_de;
cin >> n;
for(int i=1;i<n;i++){
int a, b, c;
cin >> a >> b >> c;
adj[a].pb({b,c});
adj[b].pb({a,c});
}
for(int i=1;i<=n;i++){
for(int j=0;j<2;j++){
dp2[i][j]={inf,inf};
}
}
dfs(1,1);
cal(1,1);
cout << ans << '\n';
#ifdef local
CHECK();
#endif
}
/*
*/
#ifdef local
void CHECK(){
cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
function<bool(string,string)> compareFiles = [](string p1, string p2)->bool {
std::ifstream file1(p1);
std::ifstream file2(p2);
if (!file1.is_open() || !file2.is_open())return false;
std::string line1, line2;
while (getline(file1, line1) && getline(file2, line2)) {
if (line1 != line2)return false;
}
int cnta=0,cntb=0;
while(getline(file1,line1))cnta++;
while(getline(file2,line2))cntb++;
return cntb-cnta<=1;
};
bool check = compareFiles("output.txt","expected.txt");
if (check) cerr<<"ACCEPTED\n";
else cerr<<"WRONG ANSWER!\n";
}
#else
#endif
