#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>

using namespace std;

int main()
{
  int n;
  cin >> n;
  vector<vector<pair<int, int>>> g(n);
  for (int i = 1; i < n; ++i)
  {
    int u, v, w;
    cin >> u >> v >> w;
    --u, --v;
    g[u].emplace_back(v, w);
    g[v].emplace_back(u, w);
  }
  vector<long long> dis1(n), dis2(n);
  auto bfs = [&](int s) -> vector<long long>
  {
    vector<long long> dis(n, 1e18);
    vector<int> check(n);
    check[s] = 1;
    queue<int> q;
    dis[s] = 0;
    for (q.push(s); !q.empty(); q.pop())
    {
      auto now = q.front();
      for (auto [to, c] : g[now])
      {
        if (!check[to])
        {
          dis[to] = dis[now] + c;
          check[to] = 1;
          q.push(to);
        }
      }
    }
    return dis;
  };
  dis1 = bfs(0);
  int id1 = 0;
  for (int i = 0; i < n; ++i)
  {
    if (dis1[i] > dis1[id1])
    {
      id1 = i;
    }
  }
  dis2 = bfs(id1);
  long long ans = 0;
  for (int i = 0; i < n; ++i) ans = max(ans, dis2[i]);
  cout << ans << endl;
}