#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 200200;
const ll INF = 5e17;
vector<pair<int, int>> adj[N];
ll dp[4][N];
void dfs(int v, int p = -1) {
ll mx1 = -INF, mx2 = -INF;
ll mx[3] = { -INF, -INF, -INF };
for (auto& [x, w] : adj[v]) {
if (x == p) continue;
dfs(x, v);
ll val = max({ dp[0][x], dp[1][x] + w });
// 0
dp[0][v] += max({ dp[0][x], dp[1][x] + w, dp[2][x] + w, dp[3][x] });
// 1 , 2
dp[1][v] += val;
mx1 = max(mx1, dp[0][x] + w - val);
dp[2][v] += val;
mx2 = max(mx2, max({ dp[0][x] , dp[3][x] }) + w - val);
// 3
dp[3][v] += val;
mx[1] = max(mx[1], dp[0][x] + w - val);
if (mx[0] < mx[1]) swap(mx[0], mx[1]);
mx[2] = max(mx[2], dp[3][x] + w - val);
}
dp[1][v] += mx1;
dp[2][v] += mx2;
dp[3][v] += max(mx[0] + mx[1], mx[0] + mx[2]);
}
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int n;
cin >> n;
for (int i = 1;i < n;i++) {
int u, v, w;
cin >> u >> v >> w;
adj[u].push_back({ v, w });
adj[v].push_back({ u, w });
}
dfs(1);
cout << max(dp[0][1], dp[3][1]);
return 0;
}
