#include <iostream>
#include <algorithm>
#include <functional>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <bitset>
#include <array>
#include<utility>
#include<stack>
#include <iomanip>
//#include<atcoder/all>
//using namespace atcoder;
using namespace std;
#define P pair<int,int>
#define Graph vector<vector<int>>
#define float long double
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define repi(itr,m) for(auto itr=(m).begin();itr!=(m).end();itr++)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define vi vector<int>
#define int long long
const int INF=1e18;
int dx[8]={0,1,0,-1,-1,-1,1,1};
int dy[8]={1,0,-1,0,-1,1,-1,1};
template<typename T> inline bool chmax(T &a, T b) { return ((a < b) ? (a = b, true) : (false));}
template<typename T> inline bool chmin(T &a, T b) { return ((a > b) ? (a = b, true) : (false));}
struct point{
  int x,y;
};
void yn(bool t){
  if(t)cout<<"Yes"<<endl;
  else cout<<"No"<<endl;
}
int ans=-INF;
int dfs(int n,vector<vector<P>>&g,int now,int from){
  vector<int>val;
  val.push_back(0);val.push_back(0);
  for(auto [to,cost]:g[now]){
    if(to==from)continue;
    val.push_back(dfs(n,g,to,now)+cost);
  }
  sort(rall(val));
  ans=max(ans,val[0]+val[1]);
  return val[0];
}

int solve(){
  int n;cin>>n;
  vector<vector<P>>g(n+1);
  rep(i,0,n-1){
    int u,v,w;cin>>u>>v>>w;
    g[u].push_back({v,w});
    g[v].push_back({u,w});
  }
  int k=dfs(n,g,1,0);
  
  cout<<ans<<endl;
  
  
  
  
  assert(true);
  return 0;
}

signed main(){
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  solve();
}