#include <bits/stdc++.h>
using namespace std;
using ll = long long;

ll ans = 0;

int N;
vector<vector<pair<int,ll>>> adj;

ll dfs(int v, int par) {
    vector<ll> child_vals;
    for (auto [u, w] : adj[v]) {
        if (u == par) continue;
        ll down = dfs(u, v) + w;
        child_vals.push_back(max(down, w));
    }
    if (child_vals.empty()) {
        return LLONG_MIN / 2;
    }
    sort(child_vals.rbegin(), child_vals.rend());
    // １本分
    ans = max(ans, child_vals[0]);
    // ２本分
    if (child_vals.size() >= 2) {
        ans = max(ans, child_vals[0] + child_vals[1]);
    }
    return child_vals[0];
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> N;
    adj.assign(N+1, {});
    for(int i = 1; i < N; i++){
        int u, v; ll w;
        cin >> u >> v >> w;
        adj[u].emplace_back(v, w);
        adj[v].emplace_back(u, w);
    }
    dfs(1, -1);
    cout << max(ans, 0LL) << "\n";
    return 0;
}