#include <bits/stdc++.h>

using namespace std;

#define int long long
// #define double long double
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define FORR(i, a, b) for(int i = (a); i > (b); --i)
#define REP(i, n) for(int i = 0; i < (n); ++i)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOREACH(x, a) for(auto &(x) : (a))
#define VECCIN(x)                                                              \
    for(auto &youso_ : (x)) cin >> youso_
#define bitcnt(x) __builtin_popcount(x)
#define lbit(x) __builtin_ffsll(x)
#define rbit(x) (64 - __builtin_clzll(x))
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
#define rAll(a) (a).rbegin(), (a).rend()
#define cinfast() cin.tie(0), ios::sync_with_stdio(false)
#define PERM(c)                                                                \
    sort(All(c));                                                              \
    for(bool cp = true; cp; cp = next_permutation(All(c)))
#define MKORDER(n)                                                             \
    vector<int> od(n);                                                         \
    iota(All(od), 0LL);

template <typename T = long long> inline T IN() {
    T x;
    cin >> x;
    return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&... tail) {
    cin >> head;
    CIN(move(tail)...);
}
template <class Head> inline void COUT(Head &&head) { cout << head << "\n"; }
template <class Head, class... Tail>
inline void COUT(Head &&head, Tail &&... tail) {
    cout << head << " ";
    COUT(forward<Tail>(tail)...);
}

#define CCIN(...)                                                              \
    char __VA_ARGS__;                                                          \
    CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
    double __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
    long long __VA_ARGS__;                                                     \
    CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
    string __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define Printv(v)                                                              \
    {                                                                          \
        FOREACH(x, v) { cout << x << " "; }                                    \
        cout << "\n";                                                          \
    }
template <typename T = string> inline void eputs(T s) {
    cout << s << "\n";
    exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
    std::fill((T *)array, (T *)(array + N), val);
}

// generic lambdas
template <typename F>
#if defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard)
[[nodiscard]]
#elif defined(__GNUC__) &&                                                     \
    (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 4)
__attribute__((warn_unused_result))
#endif // defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard)
    static inline constexpr decltype(auto)
    fix(F &&f) noexcept {
    return [f = std::forward<F>(f)](auto &&... args) {
        return f(f, std::forward<decltype(args)>(args)...);
    };
}

template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<ll, ll> PL;
typedef vector<PL> VPL;
typedef vector<bool> VB;
typedef vector<double> VD;
typedef vector<string> VS;

const int INF = 1e9;
const int MOD = 1e9 + 7;
// const int MOD = 998244353;
const ll LINF = 1e18;
const ll dw[] = {1, 1, 0, -1, -1, -1, 0, 1};
const ll dh[] = {0, 1, 1, 1, 0, -1, -1, -1};
#define PI 3.141592653589793238

template <typename T, typename E> struct ReRooting {
    struct Edge {
        int to;
        E data;
        T dp, ndp;
    };

    using F = function<T(T, T)>;
    using G = function<T(T, E)>;

    vector<vector<Edge>> g;
    vector<T> subdp, dp;
    const T ident;
    const F f;
    const G gg;

    ReRooting(int V, const F f, const G g, const T &ident)
        : g(V), f(f), gg(g), ident(ident), subdp(V, ident), dp(V, ident) {}

    void add_edge(int u, int v, const E &d) {
        g[u].emplace_back((Edge){v, d, ident, ident});
        g[v].emplace_back((Edge){u, d, ident, ident});
    }

    void add_edge_bi(int u, int v, const E &d, const E &e) {
        g[u].emplace_back((Edge){v, d, ident, ident});
        g[v].emplace_back((Edge){u, e, ident, ident});
    }

    void dfs_sub(int idx, int par) {
        for(auto &e : g[idx]) {
            if(e.to == par) continue;
            dfs_sub(e.to, idx);
            subdp[idx] = f(subdp[idx], gg(subdp[e.to], e.data));
        }
    }

    void dfs_all(int idx, int par, const T &top) {
        T buff{ident};
        for(int i = 0; i < (int)g[idx].size(); i++) {
            auto &e = g[idx][i];
            e.ndp = buff;
            e.dp = gg(par == e.to ? top : subdp[e.to], e.data);
            buff = f(buff, e.dp);
        }
        dp[idx] = buff;
        buff = ident;
        for(int i = (int)g[idx].size() - 1; i >= 0; i--) {
            auto &e = g[idx][i];
            if(e.to != par) dfs_all(e.to, idx, f(e.ndp, buff));
            e.ndp = f(e.ndp, buff);
            buff = f(buff, e.dp);
        }
    }

    vector<T> build() {
        dfs_sub(0, -1);
        dfs_all(0, -1, ident);
        return dp;
    }
};

signed main() {
    LCIN(N);
    auto f1 = [](PL p1, PL p2) {
        VL v = {p1.fi, p1.se, p2.fi, p2.se};
        sort(rAll(v));
        return PL(v[0], v[1]);
    };
    auto f2 = [](PL a, ll d) { return PL(max(0LL, a.fi) + d, -LINF); };
    ReRooting<PL, ll> tree(N, f1, f2, PL{-LINF, -LINF});
    REP(i, N - 1) {
        LCIN(s, t, w);
        tree.add_edge(s, t, w);
    }
    ll ans = 0;
    FOREACH(dp, tree.build()) { ans = max(ans, dp.fi + dp.se); }
    cout << ans << "\n";
}



Measured memory_bytes: 43672