#include <bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(c) (c).begin(),(c).end()
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MINF(a) memset(a,0x3f,sizeof(a))
#define POW(n) (1LL<<(n))
#define IN(i,a,b) (a <= i && i <= b)
using namespace std;
template <typename T> inline bool CHMIN(T& a,T b) { if(a>b) { a=b; return 1; } return 0; }
template <typename T> inline bool CHMAX(T& a,T b) { if(a<b) { a=b; return 1; } return 0; }
template <typename T> inline void SORT(T& a) { sort(ALL(a)); }
template <typename T> inline void REV(T& a) { reverse(ALL(a)); }
template <typename T> inline void UNI(T& a) { sort(ALL(a)); a.erase(unique(ALL(a)),a.end()); }
template <typename T> inline void LB(vector<T>& v, T& a) { return *lower_bound(ALL(v),a); }
template <typename T> inline void LBP(vector<T>& v, T& a) { return lower_bound(ALL(v),a) - v.begin(); }
template <typename T> inline void UB(vector<T>& v, T& a) { return *upper_bound(ALL(v),a); }
template <typename T> inline void UBP(vector<T>& v, T& a) { return upper_bound(ALL(v),a) - v.begin(); }
template <typename T1, typename T2> ostream& operator<< (ostream& os, const pair<T1,T2>& p) { os << p.first << " " << p.second; return os; }
template <typename T1, typename T2> istream& operator>> (istream& is, pair<T1,T2>& p) { is >> p.first >> p.second; return is; }
template <typename T> ostream& operator<< (ostream& os, const vector<T>& v) { REP(i,v.size()) { if (i) os << " "; os << v[i]; } return os; }
template <typename T> istream& operator>> (istream& is, vector<T>& v) { for(T& in : v) is >> in; return is; }
template <typename T = int> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
template< typename T, typename V > typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) { t = v; }
template< typename T, typename V > typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) { for(auto &e : t) fill_v(e, v); }
const int MOD = 1000000007;
const int INF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1e-10;

template <typename T>
struct edge {
  int s, t;
  T c;
  edge() {}
  edge(int t, T c) : s(-1), t(t), c(c) {}
  edge(int s, int t, T c) : s(s), t(t), c(c) {}
};

template <typename T> using Edges = vector<edge<T>>;
template <typename T> using WeightedGraph = vector<Edges<T>>;
using UnWeightedGraph = vector<vector<int>>;
template <typename T> using Matrix = vector<vector<T>>;

template <typename T>
pair<T, int> dfs(const WeightedGraph<T>& g, int v, int pv) {
  pair<T, int> ret(0, v);
  for (auto& e : g[v]) {
    if (e.t == pv) continue;
    auto cost = dfs(g, e.t, v);
    cost.first += e.c;
    ret = max(ret, cost);
  }
  return ret;
}

template <typename T>
T tree_diameter(const WeightedGraph<T>& g) {
  auto p = dfs(g, 0, -1);
  auto q = dfs(g, p.second, -1);
  return q.first;
}

signed main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(10);

  int n;
  cin >> n;
  WeightedGraph<int> g(n);
  REP(i,n-1) {
    int s,t,w;
    cin >> s >> t >> w;
    g[s].emplace_back(t,w);
    g[t].emplace_back(s,w);
  }
  cout << tree_diameter(g) << endl;

  return 0;
}


Measured memory_bytes: 18972