#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 2e5+5, inf = 1e18;
int n, dp[2][N];
vector<pair<int, int>> adj[N];
void dfs(int x, int p, int w) {
int sum1 = 0;
int mx = -inf;
int smx = -inf;
for (auto& [y, z] : adj[x]) {
if (y == p) continue;
dfs(y, x, z);
sum1 += dp[1][y];
int nw = dp[0][y] + z - dp[1][y];
if (nw >= mx) {
smx = mx;
mx = nw;
}
else if (nw > smx) {
smx = nw;
}
}
// no activo a nadie
dp[0][x] = dp[1][x] = sum1;
// activo a mi padre y a un hijo
dp[1][x] = max(dp[1][x], sum1 + mx + w);
// activo a dos hijos
dp[0][x] = max(dp[0][x], sum1 + mx + smx);
dp[1][x] = max(dp[1][x], sum1 + mx + smx);
}
signed main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n;
for (int i = 0; i < n-1; i++) {
int x, y, z;
cin >> x >> y >> z;
x--; y--;
adj[x].push_back(make_pair(y, z));
adj[y].push_back(make_pair(x, z));
}
dfs(0, 0, 0);
/*
for (int i = 0; i < n; i++) {
cerr << i << " " << dp[0][i] << " " << dp[1][i] << endl;
}
*/
cout << dp[0][0] << "\n";
}
