#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, a, b) for(int i = a; i < (b); i++)

int main(){
    // 入力
    int n;
    cin >> n;
    vector<vector<array<int, 2>>> tree(n);
    rep(i, 0, n-1) {
        int u, v, w;
        cin >> u >> v >> w;
        u--,v--;
        tree[u].push_back({v, w});
        tree[v].push_back({u, w});
    }

    // 木DP
    ll ans = 0;

    auto dfs = [&](auto&& dfs, int v, int p) -> ll {
        vector<ll> dists;
        for (auto [u, w] : tree[v]) {
            if (u == p) continue;
            dists.push_back(dfs(dfs, u, v) + w);
        }
        sort(dists.rbegin(), dists.rend());
        if (dists.size() == 0) {
            return 0;
        }
        if (dists.size() >= 1) {
            ans = max(ans, dists[0]);
        }
        if (dists.size() >= 2) {
            ans = max(ans, dists[0] + dists[1]);
        }
        return max(0LL, dists[0]);
        
    };

    dfs(dfs, 0, -1);

    cout << ans << endl;
}