#include <bits/stdc++.h>

using namespace std;
const int nxm = 2e5 + 10;
int n;
vector<pair<int, long long >> g[nxm];
long long dist[nxm];
void findLongestPath(int u) {
	for (auto [v, w] : g[u]) {
		if (dist[v] == -1) {
			dist[v] = dist[u] + w;
			findLongestPath(v);
		}
	}
}
int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin >> n;
	for (int i = 1; i < n; i++) {
		int u, v;
		long long w;
		cin >> u >> v >> w;
		g[u].emplace_back(v, w);
		g[v].emplace_back(u, w);
	}
	memset(dist, -1, sizeof dist);
	int firstLongest = -1;
	dist[1] = 0;
	findLongestPath(1);
	for (int i = 1; i <= n; i++) {
		if (dist[i] > dist[firstLongest]) {
			firstLongest = i;
		}
	}
	memset(dist, -1, sizeof dist);
	dist[firstLongest] = 0;
	findLongestPath(firstLongest);
	int ans = -1;
	for (int i = 1; i <= n; i++) {
		if (dist[i] > dist[ans]) {
			ans = i;
		}
	}
	cout << dist[ans] << '\n';
	return 0;
}