#include <bits/stdc++.h>
using namespace std;
#define rep(i, x, limit) for (long long i = (long long)x; i < (long long)limit; i++)
#define REP(i, x, limit) for (long long i = (long long)x; i <= (long long)limit; i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define el '\n'
#define spa " "
#define Yes cout << "Yes" << el
#define No cout << "No" << el
#define YES cout << "YES" << el
#define NO cout << "NO" << el
#define eps (1e-10)
#define Equals(a,b) (fabs((a) - (b)) < eps )
#define debug(x) cerr << #x << " = " << x << el
using ll = long long;
using ull = unsigned long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vs = vector<string>;
using vb = vector<bool>;
const double pi = 3.141592653589793238;
const int inf = 1073741823;
const ll infl = 1LL << 60;
const string ABC = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const string abc = "abcdefghijklmnopqrstuvwxyz";
const ll MOD = 998244353;
#include<atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using vm = vector<mint>;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll n;cin>>n;
  vector<vector<pll>> G(n);
  rep(i,0,n-1){
    ll u,v,w;cin>>u>>v>>w;
    u--;v--;
    G[u].emplace_back(v,w);
    G[v].emplace_back(u,w);
  }
  auto bfs=[&](ll sta)->pll{
    vb visited(n,false);
    vl dist(n,0);
    queue<ll> que;
    visited[sta]=true;
    que.push(sta);
    while(!que.empty()){
        ll v=que.front();que.pop();
        for(auto [to,w]:G[v]){
            if(visited[to])continue;
            visited[to]=true;
            dist[to]=dist[v]+w;
            que.push(to);
        }
    }
    ll a=-infl,b=-infl;
    rep(i,0,n){
        if(dist[i]>a&&i!=sta){
            a=dist[i];
            b=i;
        }
    }
    return {a,b};
  };
    pll p1=bfs(0);
    cout<<bfs(p1.second).first<<el;
}