#include <bits/stdc++.h>
using namespace std;
using i64 = long long;

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


    int n;
    cin >> n;
    vector<vector<pair<int,int>>> edges(n);
    i64 maxEdge = 0;  // for the case all weights are negative

    for(int i = 0; i < n - 1; ++i){
        int u, v, w;
        cin >> u >> v >> w;
        --u; --v;
        edges[u].emplace_back(v, w);
        edges[v].emplace_back(u, w);
        maxEdge = max(maxEdge, (i64)w);
    }

    vector<i64> dpDown(n, -1e18);
    i64 ans = maxEdge;  // at least the single largest edge if all are negative

    // dfs(u, parent): computes dpDown[u] and updates ans
    auto dfs = [&](auto&& self, int u, int p) -> void {
        // collect best "downward" contributions from children
        vector<i64> bests;
        for(auto [v, w] : edges[u]){
            if(v == p) continue;
            self(self, v, u);
            // either extend through v, or take just the edge u-v
            i64 contrib = max(dpDown[v] + w, (i64)w);
            bests.push_back(contrib);
        }
        if(bests.empty()){
            dpDown[u] = 0;
            return;
        }
        std::sort(bests.begin(), bests.end(), greater<i64>());
        i64 best1 = bests[0];
        i64 best2 = bests[1];
        ans = max(ans, best1);
        ans = max(ans, best1 + best2);
        dpDown[u] = best1;
    };

    dfs(dfs, 0, -1);
    cout << ans << "\n";
    return 0;
}