#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
const int MAXN = 200007, INF = 2000000007;
int dp[MAXN][2], N;
vector<pair<int, int>> G[MAXN];
void solve(int u, int p, int c)
{
int cur[3] = {0, -INF, -INF};
for (auto e : G[u]) {
int v = e.first, w = e.second;
if (v == p) continue;
solve(v, u, w);
cur[2] = max(cur[2] + dp[v][0], cur[1] + dp[v][1] + w);
cur[1] = max(cur[1] + dp[v][0], cur[0] + dp[v][1] + w);
cur[0] += dp[v][0];
}
dp[u][1] = max(cur[0], cur[2]);
dp[u][0] = max(dp[u][1], cur[1] + c);
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> N;
for (int i = 0; i < N - 1; ++i) {
int u, v, w;
cin >> u >> v >> w;
G[u].emplace_back(v, w);
G[v].emplace_back(u, w);
}
solve(1, 0, 0);
cout << dp[1][1] << endl;
}
