#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
template<class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i,a,n) for(int (i)=(a);(i)<(n);++(i))
#define eFOR(i,a,n) for(int (i)=(a);(i)<=(n);++(i))
#define rFOR(i,a,n) for(int (i)=(n)-1;(i)>=(a);--(i))
#define erFOR(i,a,n) for(int (i)=(n);(i)>=(a);--(i))
#define each(i, a) for(auto &i : a)
#define SORT(i) sort((i).begin(),(i).end())
#define rSORT(i,a) sort((i).begin(),(i).end(),(a))
#define all(i) (i).begin(),(i).end()
#define out(y,x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define line cout << "-----------------------------\n" 
#define ENDL(i,n) ((i) == (n) - 1 ? "\n" : " ")
//#define stop system("pause")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr ld pi = 3.1415926535897932;
template<class T>inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T>inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; }return false; }
inline void init() { cin.tie(nullptr); cout.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); }
template<class T>inline istream& operator>>(istream& is, vector<T>& v) { for (auto& elemnt : v)is >> elemnt; return is; }
template<class T>inline istream& operator>>(istream& is, deque<T>& v) { for (auto& elemnt : v)is >> elemnt; return is; }
template<class T, class U>inline istream& operator>>(istream& is, pair<T, U>& p) { is >> p.first >> p.second; return is; }
template<class T>inline vector<T> vec(size_t a) { return vector<T>(a); }
template<class T>inline vector<T> defvec(T def, size_t a) { return vector<T>(a, def); }
template<class T, class... Ts>inline auto vec(size_t a, Ts... ts) { return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...)); }
template<class T, class... Ts>inline auto defvec(T def, size_t a, Ts... ts) { return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...)); }

template<class T> class rerooting {
    using F1 = function<T(const T&, const T&)>;
    using F2 = function<T(const T&, int)>;
    T m_unit, p_unit;
    F1 merge;
    F2 pushup;

    vector<vector<pair<int, int>>>& g;
    int n;
    vector<vector<T>> l, r;
    vector<T> dp, ans;
public:
    rerooting(vector<vector<pair<int, int>>>& _g, T unit1, F1 fun1, T unit2, F2 fun2)
        : g(_g), n(g.size()), l(n), r(n), dp(n), ans(n),
        m_unit(unit1), merge(fun1), p_unit(unit2), pushup(fun2) {
        dfs1(0, -1), dfs2(0, p_unit);
    }
    void dfs1(int now, int par) {
        l[now].reserve(g[now].size());
        r[now].reserve(g[now].size());
        l[now].push_back(m_unit);
        if (par != -1)each(dest, g[now]) {
            if (dest.first == par) {
                g[now].erase(find(all(g[now]), dest));
                break;
            }
        }
        each(dest, g[now]) {
            dfs1(dest.first, now);
            l[now].push_back(pushup(dp[dest.first], dest.second));
        }
        FOR(i, 2, l[now].size())r[now].push_back(l[now][i]);
        r[now].push_back(m_unit);
        FOR(i, 1, l[now].size())l[now][i] = merge(l[now][i - 1], l[now][i]);
        rFOR(i, 0, r[now].size() - 1)r[now][i] = merge(r[now][i + 1], r[now][i]);
        dp[now] = l[now].back();
        l[now].pop_back();
    }
    void dfs2(int now, const T& pardp) {
        ans[now] = merge(pardp, dp[now]);
        FOR(i, 0, g[now].size()) {
            dfs2(g[now][i].first, pushup(merge(merge(l[now][i], r[now][i]), pardp), g[now][i].second));
        }
    }
    void print(string s) {
        int res = 0;
        FOR(i, 0, n)chmax(res, ans[i].first + ans[i].second);
        cout << res << s;
    }
};

using P = pair<int, int>;
int main() {
    init();

    int n; cin >> n;
    auto g = vec<vector<P>> (n);
    FOR(i, 0, n - 1) {
        int a, b, c; cin >> a >> b >> c;
        g[a].emplace_back(b, c);
        g[b].emplace_back(a, c);
    }

    rerooting<P>(g,
        P(0, 0), [](const P& a, const P& b)->P {
            return P(max(a.first, a.second), max(b.first, b.second)); },
        P(0, 0), [](const P& a, int wei)->P { return P(a.first + wei, a.second + wei); }
        ).print("\n");
}


Measured memory_bytes: 31768