#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    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);
    }
    queue<int> que;
    auto bfs = [&](int v){
        vector<ll> dp(n);
        vector<bool> used(n);
        dp[v] = 0;
        used[v] = true;
        que.emplace(v);
        while(!que.empty()){
            v = que.front();
            que.pop();
            for(auto [u, w] : g[v]){
                if(used[u]) continue;
                used[u] = true;
                dp[u] = dp[v] + w;
                que.emplace(u);
            }
        }
        return dp;
    };
    auto dp0 = bfs(0);
    auto dp1 = bfs(max_element(dp0.begin(), dp0.end()) - dp0.begin());
    cout << *max_element(dp1.begin(), dp1.end()) << '\n';
}