#include<iostream>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<queue>
#include<set>
#include<map>
using namespace std;
#define OVERLOAD_REP(_1, _2, _3, name, ...) name
#define REP1(i, n) for (auto i = std::decay_t<decltype(n)>{}; (i) != (n); ++(i))
#define REP2(i, l, r) for (auto i = (l); (i) != (r); ++(i))
#define rep(...) OVERLOAD_REP(__VA_ARGS__, REP2, REP1)(__VA_ARGS__)
#define REP(i, l, r) rep(i, l, r+1)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
using ll = long long;
using ld = long double;
using P = pair<ll,ll>;
//using Graph = vector<vector<Edge> >;
const ll INF = 2e18;
//const int INF = 2e9;
template<class T> using vc = vector<T>;
template<class T> using vv = vector<vector<T> >;
template<class T> using vvv = vector<vector<vector<T> > >;
template<class T> using pq = priority_queue<T>;
template<class T> using pq_g = priority_queue<T, vc<T>, greater<T> >;
template<class T> istream& operator>>(istream& i, vc<T>& v) { rep(j, 0, v.size()) i>>v[j]; return i; }
template<class T> ostream& operator<<(ostream& o, vc<T>& v) { rep(j, 0, v.size()) o<<v[j]<<" "; return o; }
template<class T> bool chmin(T& a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> bool chmax(T& a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

template <typename T>
struct Edge {
    int to;
    T cost;
};
using Graph = vector<vector<Edge<long long>>>;  // cost の型を long long に指定
/* tree_diamiter : dfs を用いて重み付き木 T の直径を求める
    計算量: O(N)
*/
template <typename T>
pair<T, int> dfs(const Graph &G, int u, int par) {  // 最遠点間距離と最遠点を求める
    pair<T, int> ret = make_pair((T)0, u);
    for (auto e : G[u]) {
        if (e.to == par) continue;
        auto next = dfs<T>(G, e.to, u);
        next.first += e.cost;
        ret = max(ret, next);
    }
    return ret;
}
template <typename T>
T tree_diamiter(const Graph &G) {
    pair<T, int> p = dfs<T>(G, 0, -1);
    pair<T, int> q = dfs<T>(G, p.second, -1);
    return q.first;
}

int main() {
    // 高速化
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    // 小数点の出力桁数を指定
    cout << fixed << setprecision(10);

    // メイン
    int N;
    cin >> N;
    Graph G(N);
    rep(i, 0, N-1) {
        int u, v;
        ll w;
        cin >> u >> v >> w;
        u--, v--;
        G[u].push_back({v, w});
        G[v].push_back({u, w});
    }
    cout << tree_diamiter<ll>(G) << endl;


    return 0;
}