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

using ll = long long;
const int MAXN = 200005;

vector<pair<int, ll>> graph[MAXN];

struct Result {
    int node;
    ll dist;
};

Result dfs(int node, int parent, ll dist) {
    Result res = {node, dist};
    for (auto [next, weight] : graph[node]) {
        if (next == parent) continue;
        Result tmp = dfs(next, node, dist + weight);
        if (tmp.dist > res.dist) {
            res = tmp;
        }
    }
    return res;
}

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

    int n;
    cin >> n;

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

    Result r1 = dfs(1, -1, 0);

    Result r2 = dfs(r1.node, -1, 0);

    cout << max(r2.dist, 0LL) << '\n';

    return 0;
}