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

int main() {
  int n;
  std::cin >> n;
  std::vector adj(n, std::vector<std::pair<long long, int>>());
  for(int i = 0; i < n-1; i++) {
    int u, v, w;
    std::cin >> u >> v >> w;
    u--; v--;
    adj[u].emplace_back(w, v);
    adj[v].emplace_back(w, u);
  }
  auto dfs = [&](auto&& self, int v, int p) -> std::pair<long long, long long> {
    // {自分を端に含むもの, 含まないもの}
    std::pair<long long, long long> res = {0, 0};
    std::vector<long long> children_score;
    for(auto [w, u] : adj[v]) {
      if(u == p) continue;
      auto [contain, not_contain] = self(self, u, v);
      res.first = std::max(res.first, contain + w);
      children_score.push_back(contain + w);
      res.second = std::max(res.second, not_contain);
    }
    std::sort(children_score.rbegin(), children_score.rend());
    if(children_score.size() >= 1)
      res.second = std::max(res.second, children_score[0]);
    if(children_score.size() >= 2)
      res.second = std::max(res.second, children_score[0] + children_score[1]);

    return res;
  };
  auto [contain, not_contain] = dfs(dfs, 0, -1);
  std::cout << std::max(contain, not_contain) << std::endl;
}