#include <bits/stdc++.h>

#include <atcoder/all>
using namespace std;
using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;
#define FAST_IO                \
  ios::sync_with_stdio(false); \
  cin.tie(0);
const i64 INF = 1001001001001001001;
using Modint = atcoder::static_modint<998244353>;

pair<int, i64> farthest_node(int start, const vector<vector<pair<int, i64>>>& g) {
  vector<i64> dist(g.size(), INF);
  int N = g.size();
  vector<bool> visited(N);
  queue<int> q;
  q.push(start);
  visited[start] = true;
  dist[start] = 0;
  int farthest = start;
  i64 max_dist = 0;

  while (!q.empty()) {
    int node = q.front();
    q.pop();
    for (auto [next, weight] : g[node]) {
      if (!visited[next]) {
        visited[next] = true;
        dist[next] = dist[node] + weight;
        q.push(next);
        if (dist[next] > max_dist) {
          max_dist = dist[next];
          farthest = next;
        }
      }
    }
  }
  return {farthest, max_dist};
}

i64 diameter(const vector<vector<pair<int, i64>>>& g) {
  int N = g.size();
  auto [farthest, _] = farthest_node(0, g);
  return farthest_node(farthest, g).second;
}

int main() {
  FAST_IO
  auto ans = 0LL;

  int N;
  cin >> N;
  vector<int> u(N-1), v(N-1);
  vector<i64> w(N-1);
  for (int i = 0; i < N - 1; i ++) {
    cin >> u[i] >> v[i] >> w[i];
    u[i] --;
    v[i] --;
  }

  vector<vector<pair<int, i64>>> g(N);
  for (int i = 0; i < N - 1; i ++) {
    g[u[i]].emplace_back(v[i], w[i]);
    g[v[i]].emplace_back(u[i], w[i]);
  }

  ans = diameter(g);

  cout << ans << endl;
}