#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

using ll = long long;
using P = pair<int, ll>;

int N;
vector<vector<P>> G;

vector<bool> visited;
ll max_dist = 0;
int far_node = 0;

void dfs(int node, ll dist) {
    visited[node] = true;
    if (dist > max_dist) {
        max_dist = dist;
        far_node = node;
    }
    for (auto [to, w] : G[node]) {
        if (!visited[to]) {
            dfs(to, dist + w);
        }
    }
}

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

    cin >> N;
    G.resize(N + 1);  // 1-indexed

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

    // 1回目のDFS
    visited.assign(N + 1, false);
    max_dist = 0;
    dfs(1, 0);

    // 2回目のDFS
    visited.assign(N + 1, false);
    max_dist = 0;
    dfs(far_node, 0);

    cout << max_dist << '\n';

    return 0;
}