#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>
T dfs(const WeightedGraph<T> &g, int u, int parent, T &result) {
  T best1 = 0;
  T best2 = 0;

  for(auto &e : g[u]) {
    if(e.to == parent) continue;
    T child_best = dfs(g, e.to, u, result) + e.cost;
    if(child_best > best1) {
      best2 = best1;
      best1 = child_best;
    } else if(child_best > best2) {
      best2 = child_best;
    }
  }

  result = max(result, best1 + best2);
  return best1;
}

template< typename T >
T tree_diameter(const WeightedGraph<T> &g) {
  if (g.size() <= 1) return 0;
  T result = numeric_limits<T>::lowest();
  dfs(g, 0, -1, result);
  return result;
}

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 << tree_diameter(g) << endl;
}