#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

struct Edge {
    int to, weight;
};

vector<Edge> graph[100005];
bool visited[100005];
int dist[100005];

// DFSを使って最長のパスを探す
int dfs(int node) {
    visited[node] = true;
    int max1 = 0, max2 = 0;

    for (auto& edge : graph[node]) {
        int nextNode = edge.to;
        int weight = edge.weight;
        if (!visited[nextNode]) {
            int d = dfs(nextNode) + weight;
            if (d > max1) {
                max2 = max1;
                max1 = d;
            } else if (d > max2) {
                max2 = d;
            }
        }
    }

    dist[node] = max1;  // 最大距離を保存
    return max1;  // 最大距離を返す
}

int main() {
    int N;
    cin >> N;

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

    memset(visited, 0, sizeof(visited));

    // 1回目のDFSで最も遠い頂点を見つける
    dfs(0);

    int farthestNode = -1;
    int maxDist = -1;
    for (int i = 0; i < N; ++i) {
        if (dist[i] > maxDist) {
            maxDist = dist[i];
            farthestNode = i;
        }
    }

    // 2回目のDFSで直径を求める
    memset(visited, 0, sizeof(visited));
    memset(dist, 0, sizeof(dist));

    dfs(farthestNode);

    int diameter = *max_element(dist, dist + N);

    cout << diameter << endl;

    return 0;
}