// clang-format off
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define main signed main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979;
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int n) { return n & 1; }
constexpr bool even(const int n) { return ~n & 1; }
template<typename T = int> T in() { T x; cin >> x; return x; }
template<typename T = int> T in(T &&x) { T z(forward<T>(x)); cin >> z; return z; }
template<typename T> istream &operator>>(istream &is, vector<T> &v) { for (T &x : v) is >> x; return is; }
template<typename A, typename B> istream &operator>>(istream &is, pair<A, B> &p) { return is >> p.first >> p.second; }
template<typename T> ostream &operator<<(ostream &os, const vector<vector<T>> &v) { int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "" : "\n"); return os; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v) { int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "" : " "); return os; }
template<typename A, typename B> ostream &operator<<(ostream &os, const pair<A, B> &p) { return os << p.first << ' ' << p.second; }
template<typename Head, typename Value> auto vectors(const Head &head, const Value &v) { return vector<Value>(head, v); }
template<typename Head, typename... Tail> auto vectors(Head x, Tail... tail) { auto inner = vectors(tail...); return vector<decltype(inner)>(x, inner); }
// clang-format on

using Weight = int;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(const int s = 0, const int d = 0, const Weight w = 0) : src(s), dst(d), weight(w) {}
};

using Edges = std::vector<Edge>;
using Array = std::vector<Weight>;
using Matrix = std::vector<Array>;

class Graph {
  std::vector<Edges> g;
  using iterator = std::vector<Edges>::iterator;
  using const_iterator = std::vector<Edges>::const_iterator;

public:
  Graph(const int size = 0) : g(size) {}
  size_t size() const { return g.size(); }
  const Edges &operator[](const int i) const { return g[i]; }
  void addArc(const int src, const int dst, const Weight w = 1) { g[src].emplace_back(src, dst, w); }
  void addEdge(const int node1, const int node2, const Weight w = 1) {
    addArc(node1, node2, w);
    addArc(node2, node1, w);
  }
  iterator begin() { return g.begin(); }
  const_iterator begin() const { return g.begin(); }
  iterator end() { return g.end(); }
  const_iterator end() const { return g.end(); }
};

Edge diameterOfTree(const Graph &g) {
  Weight inf = std::numeric_limits<Weight>::max() / 8;
  int n = g.size();
  auto bfs = [&](int s) {
    std::vector<Weight> dist(n, inf);
    dist[s] = 0;
    std::queue<int> q;
    for (q.push(s); q.size(); q.pop()) {
      int u = q.front();
      for (auto &e : g[u]) {
        int v = e.dst;
        if (dist[v] == inf) {
          dist[v] = dist[u] + e.weight;
          q.push(v);
        }
      }
    }
    return dist;
  };
  std::vector<Weight> dist = bfs(0);
  int u = -1, v = -1;
  rep(i, n) if (dist[i] != inf && (u == -1 || dist[u] < dist[i])) u = i;
  dist = bfs(u);
  rep(i, n) if (dist[i] != inf && (v == -1 || dist[v] < dist[i])) v = i;
  Weight d = dist[v];
  if (u > v) std::swap(u, v);
  return Edge(u, v, d);
}

main {
  int n;
  cin >> n;
  Graph g(n);
  rep(i, n - 1) {
    int u, v, d;
    cin >> u >> v >> d;
    g.addEdge(u, v, d);
  }
  cout << diameterOfTree(g).weight << endl;
}



Measured memory_bytes: 14240