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

const int iinf = 1e9;
const ll inf = 1e18;

template<typename T>
ostream& operator<<(ostream &o, vector<T> v) {
    for (int i = 0; i < v.size(); i++)
        o << v[i] << (i+1<v.size()?" ":"");
    return o;
}

struct Edge { int to; ll cost; };

int main() {
    cin.tie(0)->sync_with_stdio(false);
    int n;
    cin >> n;
    vector<vector<Edge>> g(n);
    for (int i = 0; i < n-1; i++) {
        int u, v;
        ll w;
        cin >> u >> v >> w;
        u--, v--;
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    auto farthest = [&](int src){
        vector<ll> dist(n+1, -1);
        queue<int> q;
        dist[src] = 0;
        q.push(src);
        int far_node = src;
        while(!q.empty()){
            int v = q.front(); q.pop();
            for(auto [u, w] : g[v]){
                if(dist[u] == -1){
                    dist[u] = dist[v] + w;
                    q.push(u);
                    if(dist[u] > dist[far_node]){
                        far_node = u;
                    }
                }
            }
        }
        return pair<int,ll>(far_node, dist[far_node]);
    };

    auto [x, _] = farthest(0);
    auto [y, ans] = farthest(x);
    cout << ans << endl;
    return 0;
}