#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <string>
#include <map>
#include <set>
#include <limits>

using namespace std;

#define rep(i, n) for (int i = 0; i < (n); i++)

typedef long long ll;

template<typename T>
struct Edge {
  int to;
  T cost;
};

template< typename T >
using WeightedGraph = vector<vector<Edge<T>>>;

template< typename T >
tuple<T, int, int> dfs(const WeightedGraph< T > &g, int idx, int par) {
  tuple<T, int, int> ret(numeric_limits<T>::lowest(), idx, 0);
  bool has_child = false;
  
  for(auto &e : g[idx]) {
    if(e.to == par) continue;
    has_child = true;
    auto cost = dfs(g, e.to, idx);
    std::get<0>(cost) += e.cost;
    std::get<2>(cost) += 1;
    if (std::get<0>(cost) > std::get<0>(ret) || 
        (std::get<0>(cost) == std::get<0>(ret) && std::get<2>(cost) < std::get<2>(ret))) {
        ret = cost;
    }
  }
  
  if (!has_child) {
    return make_tuple(0, idx, 0);
  }
  return ret;
}

template< typename T >
T tree_diameter(const WeightedGraph< T > &g) {
  if (g.size() <= 1) return 0;
  auto p = dfs(g, 0, -1);
  auto q = dfs(g, std::get<1>(p), -1);
  return std::get<0>(q);
}

signed main() {
    int N; cin >> N;
    WeightedGraph<ll> g(N);
    rep(i, N - 1) {
        int u, v; ll w; cin >> u >> v >> w;
        u--; v--;
        g[u].emplace_back(Edge<ll>{v, w});
        g[v].emplace_back(Edge<ll>{u, w});
    }
    cout << std::max(0LL, tree_diameter(g)) << endl;
}