#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>

# define int long long
using namespace std;

int n;
vector<vector<pair<int, int>>> graph;

pair<int, int> bfs(int start) {
    vector<int> dist(n + 1, -1);
    queue<int> q;

    dist[start] = 0;
    q.push(start);

    while (!q.empty()) {
        int node = q.front(); q.pop();
        for (auto [neighbor, weight] : graph[node]) {
            if (dist[neighbor] == -1) {
                dist[neighbor] = dist[node] + weight;
                q.push(neighbor);
            }
        }
    }

    int max_dist = 0, farthest_node = start;
    for (int i = 1; i <= n; ++i) {
        if (dist[i] > max_dist) {
            max_dist = dist[i];
            farthest_node = i;
        }
    }

    return {farthest_node, max_dist};
}

signed main() {
    cin >> n;
    graph.resize(n + 1);

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

    auto [u, dist1] = bfs(1);
    auto [v, diameter] = bfs(u);

    cout << diameter << endl;

    return 0;
}