#include<bits/stdc++.h>
using ll = long long;
#define var auto
const char newl = '\n';

using namespace std;

bool solve(){
  
  return true;
}

ll res = 0;
vector<vector<pair<int, ll>>> g;

ll solve(ll node, ll par) {
  ll mx1 = 0, mx2 = 0;
  for (var [adj, w] : g[node]) {
    if (adj == par) continue;
    var nxt = solve(adj, node) + w;
    if (mx1 < nxt) {
      mx2 = mx1;
      mx1 = nxt;
    }
    else if (mx2 < nxt) {
      mx2 = nxt;
    }
  }
  res = max(res, mx1 + mx2);
  return mx1;
}

int main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);
  int n;
  cin >> n;
  g = vector<vector<pair<int, ll>>>(n);
  for (int i = 0; i < n - 1; i++) {
    int u, v, w;
    cin >> u >> v >> w; u--; v--;
    g[u].emplace_back(v, w);
    g[v].emplace_back(u, w);
  }

  solve(0, -1);
  cout << res << endl;
}