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

using ll = long long;
const ll LLINF = 1LL << 60;

int main() {
	int N;
	cin >> N;
	vector<vector<pair<int, ll>>> G(N);
	for(int i = 0; i < N - 1; i++) {
		int u, v, w;
		cin >> u >> v >> w;
		u--, v--;
		G[u].emplace_back(v, w);
		G[v].emplace_back(u, w);
	}
	vector<ll> dp(N);
	auto dfs1 = [&](auto&& self, int u, int p) -> void {
		ll res = 0;
		for(auto [v, w] : G[u]) {
			if(v == p) continue;
			self(self, v, u);
			res = max(res, dp[v] + w);
		}
		dp[u] = res;
	};
	dfs1(dfs1, 0, -1);
	vector<ll> ans(N);
	auto dfs2 = [&](auto&& self, int u, int p) -> void {
		ans[u] = dp[u];
		int sz = G[u].size();
		vector<ll> lmax(sz + 1, -LLINF);
		for(int i = 0; i < sz; i++) {
			auto [v, w] = G[u][i];
			lmax[i + 1] = max(lmax[i], dp[v] + w);
		}
		vector<ll> rmax(sz + 1, -LLINF);
		for(int i = sz - 1; i >= 0; i--) {
			auto [v, w] = G[u][i];
			rmax[i] = max(rmax[i + 1], dp[v] + w);
		}
		for(int i = 0; i < sz; i++) {
			auto [v, w] = G[u][i];
			if(v == p) continue;
			ll dpu = dp[u], dpv = dp[v];
			dp[u] = max(lmax[i], rmax[i + 1]);
			dp[v] = max(dp[v], dp[u] + w);
			self(self, v, u);
			dp[u] = dpu;
			dp[v] = dpv;
		}
	};
	dfs2(dfs2, 0, -1);
	cout << (*max_element(ans.begin(), ans.end())) << endl;
}