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

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

int n;
vector<vector<P>> tree;
vector<bool> visited;

ll max_dist = 0;
int farthest_node = 0;

void dfs(int node, ll dist) {
    visited[node] = true;
    if (dist > max_dist) {
        max_dist = dist;
        farthest_node = node;
    }

    for (auto [next, weight] : tree[node]) {
        if (!visited[next]) {
            dfs(next, dist + weight);
        }
    }
}

int main() {
    cin >> n;
    tree.resize(n + 1);

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

    visited.assign(n + 1, false);
    dfs(1, 0);  // 適当な頂点（1）から最も遠い点を見つける

    visited.assign(n + 1, false);
    max_dist = 0;
    dfs(farthest_node, 0);  // その点からもう一度DFS

    cout << max_dist << endl;  // 木の直径
    return 0;
}