#include<bits/stdc++.h>
using namespace std;
#define Sz(x) (x).size()
#define All(x) (x).begin(), (x).end()
const int N = 2e5 + 10;
const long long INF = 1e18;
long long dp[N][4];
vector<pair<int, int> > adj[N];
void DFS(int x, int p = 0, int cnt = 0) {
for(auto [j, t] : adj[x]) {
if(j == p) continue;
DFS(j, x, t);
}
if(Sz(adj[x]) == 1 && x != 1) {
return;
}
vector<long long> vc;
long long sum = 0;
for(auto [j, t] : adj[x]) {
if(j == p) continue;
sum += dp[j][1];
}
// ba babash
long long mx = -INF, mx2 = -INF;
for(auto [j, t] : adj[x]) {
if(j == p) continue;
mx = max(mx, max(dp[j][2], dp[j][3]) + t - dp[j][1]);
mx2 = max(mx2, dp[j][3] + t - dp[j][1]);
}
dp[x][0] = max(dp[x][0], sum + mx + cnt);
dp[x][1] = max(dp[x][1], sum + mx2 + cnt);
// ba bachash
long long ind = 0; mx = -INF;
for(auto [j, t] : adj[x]) {
if(j == p) continue;
if((dp[j][2] - dp[j][1] + t >= mx) || ind == 0) {
mx = dp[j][2] - dp[j][1] + t;
ind = j;
}
}
vc.clear();
for(auto [j, t] : adj[x]) {
if(j == ind || j == p) continue;
vc.push_back(dp[j][3] + t - dp[j][1]);
}
sort(All(vc), greater<long long>());
if(Sz(vc) > 0) {
dp[x][0] = max(dp[x][0], sum + mx + vc[0]);
dp[x][2] = max(dp[x][2], sum + mx + vc[0]);
}
if(Sz(vc) > 1) {
dp[x][0] = max(dp[x][0], sum + vc[1] + vc[0]);
dp[x][2] = max(dp[x][2], sum + vc[1] + vc[0]);
}
ind = 0; mx = -INF;
for(auto [j, t] : adj[x]) {
if(j == p) continue;
if((dp[j][3] - dp[j][1] + t >= mx) || ind == 0) {
mx = dp[j][3] - dp[j][1] + t;
ind = j;
}
}
vc.clear();
for(auto [j, t] : adj[x]) {
if(j == ind || j == p) continue;
vc.push_back(dp[j][2] + t - dp[j][1]);
}
sort(All(vc), greater<long long>());
if(Sz(vc) > 0) {
dp[x][0] = max(dp[x][0], sum + mx + vc[0]);
dp[x][2] = max(dp[x][2], sum + mx + vc[0]);
}
// hich kodom
mx = -INF;
for(auto [j, t] : adj[x]) {
if(j == p) continue;
mx = max(mx, dp[j][0] - dp[j][1]);
}
for(int i = 0; i < 4; i++) dp[x][i] = max(dp[x][i], sum);
dp[x][0] = max(dp[x][0], sum + mx);
dp[x][2] = max(dp[x][2], sum + mx);
}
int main() {
int n; cin >>n;
for(int i = 0; i < n - 1; i++) {
int u, v, c; cin >>u >>v >>c;
adj[u].push_back({v, c}), adj[v].push_back({u, c});
}
DFS(1);
/*for(int i = 1; i <= n; i++) {
cout<<"^^" <<i <<' ' <<dp[i][0] <<' ' <<dp[i][1] <<' ' <<dp[i][2] <<' ' <<dp[i][3] <<endl;
}*/
cout<<dp[1][2] <<endl;
}
