#include <bits/stdc++.h>
using namespace std;

template <typename T>
struct Edge {
    int to;
    T cost;
};
using Graph = vector<vector<Edge<long long>>>; 
template <typename T>
pair<T, int> dfs(const Graph &G, int u, int par) { 
    pair<T, int> ret = make_pair((T)0, u);
    for (auto e : G[u]) {
        if (e.to == par) continue;
        auto next = dfs<T>(G, e.to, u);
        next.first += e.cost;
        ret = max(ret, next);
    }
    return ret;
}
template <typename T>
T tree_diamiter(const Graph &G) {
    pair<T, int> p = dfs<T>(G, 0, -1);
    pair<T, int> q = dfs<T>(G, p.second, -1);
    return q.first;
}

int main() {
	int n; std::cin >> n;
	Graph G(n);

	for(int i : std::views::iota(0, n - 1)) {
		int u, v, w; std::cin >> u >> v >> w; --u, --v;
		G[u].emplace_back(v, w);
		G[v].emplace_back(u, w);
	}

	std::cout << tree_diamiter<long>(G) << "\n";
}