/**
* author: wxhtzdy
* created: 01.07.2022 14:47:42
**/
#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
vector<vector<pair<int, int>>> g(n);
for (int i = 0; i < n - 1; i++) {
int u, v, w;
cin >> u >> v >> w;
--u; --v;
g[u].emplace_back(v, w);
g[v].emplace_back(u, w);
}
vector<vector<vector<long long>>> dp(n, vector<vector<long long>>(2, vector<long long>(2)));
function<void(int, int, int)> Dfs = [&](int v, int pr, int up) {
vector<long long> f;
long long ft = 0;
for (auto& p : g[v]) {
int u = p.first;
int w = p.second;
if (u == pr) {
continue;
}
Dfs(u, v, w);
ft += max(dp[u][0][1], dp[u][1][1]);
f.push_back(w + max(dp[u][0][0], dp[u][0][1]) - max(dp[u][0][1], dp[u][1][1]));
}
dp[v][0][1] = ft;
sort(f.rbegin(), f.rend());
if ((int) f.size() >= 2) {
dp[v][0][0] = max(ft, ft + f[0] + f[1]);
} else {
dp[v][0][0] = ft;
}
if ((int) f.size() >= 1) {
dp[v][1][1] = ft + up + f[0];
}
};
Dfs(0, 0, 0);
long long ans = max(dp[0][0][0], dp[0][0][1]);
for (int i = 1; i < n; i++) {
for (int p = 0; p < 2; p++) {
for (int q = 0; q < 2; q++) {
ans = max(ans, dp[i][p][q]);
}
}
}
cout << ans << '\n';
return 0;
}
