#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll LINF = 4321001001001001001;
struct graph {
	struct edge {
		int to;
		ll cost;
	};
	vector<vector<edge>> g;
	vector<ll> dist;
	int n;
	graph(int n_) : g(n_), dist(n_, LINF), n(n_) {}
	void addEdge(int from, int to, ll cost) {
		g[from].push_back(edge{to, cost});
	}
	void addEdgeBoth(int n1, int n2, ll cost) {
		addEdge(n1, n2, cost);
		addEdge(n2, n1, cost);
	}
	void dijkstra(int st) {
		for (int i = 0; i < n; i++) dist[i] = LINF;
		// priority_queue qv
		// first: distance from st
		// second: this node
		using qv = pair<ll, int>;
		priority_queue<qv, vector<qv>, greater<qv>> q;
		dist[st] = 0;
		q.push(qv{dist[st], st});
		while (!q.empty()) {
			qv now = q.top();
			q.pop();
			if (now.first > dist[now.second]) continue;
			for (edge ne : g[now.second]) {
				ll nd = dist[now.second] + ne.cost;
				if (dist[ne.to] > nd) {
					dist[ne.to] = nd;
					q.push(qv{dist[ne.to], ne.to});
				}
			}
		}
		return;
	}
};
int main() {
	int n;
	cin >> n;
	graph g(n);
	for (int i = 0; i < n - 1; i++) {
		int u, v, w;
		cin >> u >> v >> w;
		u--;
		v--;
		g.addEdgeBoth(u, v, w);
	}
	ll ans = 0;
	auto f = [&](auto self, int i, int prev = -1) -> ll {
		vector<ll> vs;
		for (auto [j, c] : g.g[i]) {
			if (j == prev) continue;
			vs.push_back(self(self, j, i) + c);
		}
		vs.push_back(0);
		sort(vs.rbegin(), vs.rend());
		if (vs.size() == 1) {
			ans = max(ans, vs[0]);
		} else {
			ans = max(ans, vs[0] + vs[1]);
		}
		return vs[0];
	};
	f(f, 0);
	cout << ans << endl;
	return 0;
}