#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001LL
long long dp[300000];
long long ans = 0;

void dfs(int v,int p,vector<vector<pair<int,long long>>> &E){
	vector<long long> t;
	rep(i,E[v].size()){
		int to = E[v][i].first;
		long long c = E[v][i].second;
		if(to == p) continue;
		dfs(to,v,E);
		t.push_back(dp[to]+c);
	}
	sort(t.rbegin(),t.rend());
	if(t.size()>=2)ans = max(ans,t[0]+t[1]);
	if(t.size()>=1){
		ans = max(ans,t[0]);
		dp[v] = max(t[0],0LL);
	}
}
int main(){
	
	int n;
	cin>>n;
	vector<vector<pair<int,long long>>> E(n);
	rep(i,n-1){
		int a,b;
		long long c;
		cin>>a>>b>>c;
		a--;
		b--;
		E[a].push_back({b,c});
		E[b].push_back({a,c});
	}
	dfs(0,-1,E);
	cout<<ans<<endl;
	return 0;
}