#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 u) -> Edge {
        vector<ll> d(n, inf);
        d[u] = 0;
        queue<int> q;
        q.push(u);
        while (!q.empty()) {
            int v = q.front(); q.pop();
            for (auto e : g[v]) {
                if (d[e.to] != inf) continue;
                if (d[e.to] > d[v] + e.cost) {
                    d[e.to] = d[v] + e.cost;
                    if (e.to != u) q.push(e.to);
                }
            }
        }
        int mi = 0;
        for (int i = 0; i < n; i++) {
            if (d[i] > d[mi]) mi = i;
        }
        return {mi, d[mi]};
    };
    auto [x, _] = farthest(0);
    auto [y, ans] = farthest(x);
    cout << ans << endl;
    return 0;
}