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

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ll, int> pli;
typedef pair<int, int> pii;
typedef pair<ll, ld> pld;
typedef pair<pii, int> ppiii;
typedef pair<pii, ll> ppiil;
typedef pair<pll, ll> pplll;
typedef vector<vector<ll>> vvl;
typedef vector<vector<int>> vvi;
#define rep(i, a, b) for (ll i=(a); i<(b); i++)
#define rrep(i, a, b) for (ll i=(a); i>(b); i--)
#define btoe(obj) (obj).begin(), (obj).end()
#define pb push_back
#define str to_string
#define mkp make_pair
const ll INF = 1e18;
const ll MOD = 1e9 + 7;
template<typename T> inline bool chmax(T &x, T y) { return (y > x) ? x = y, true : false; }
template<typename T> inline bool chmin(T &x, T y) { return (y < x) ? x = y, true : false; }

template<typename T>
void print(T out) {
    cout << out << '\n';
}

void print(ld out) {
    cout << fixed << setprecision(12) << out << '\n';
}

template<typename T1, typename T2>
void print(pair<T1, T2> out) {
    cout << out.first << ' ' << out.second << '\n';
}

template<typename T>
void print(vector<T> A) {
    rep(i, 0, A.size()) {
        cout << A[i];
        cout << (i == A.size()-1 ? '\n' : ' ');
    }
}

template<typename T>
void print(set<T> S) {
    vector<T> A(btoe(S));
    print(A);
}

ll sum(vector<ll> A) {
    ll res = 0;
    for (ll a: A) res += a;
    return res;
}

ll max(vector<ll> A) {
    ll res = -INF;
    for (ll a: A) chmax(res, a);
    return res;
}

ll min(vector<ll> A) {
    ll res = INF;
    for (ll a: A) chmin(res, a);
    return res;
}

ll sum(ll A[], int len) {
    ll res = 0;
    rep(i, 0, len) res += A[i];
    return res;
}

ll max(ll A[], int len) {
    ll res = -INF;
    rep(i, 0, len) chmax(res, A[i]);
    return res;
}

ll min(ll A[], int len) {
    ll res = INF;
    rep(i, 0, len) chmin(res, A[i]);
    return res;
}

ll toint(string s) {
    ll res = 0;
    for (char c : s) {
        res *= 10;
        res += (c - '0');
    }
    return res;
}

int toint(char c) {
    return c - '0';
}

ll pow(ll x, ll n, int mod) {
    ll res = 1;
    while (n > 0) {
        if (n & 1) {
            res = (res * x) % mod;
        }
        x = (x * x) % mod;
        n >>= 1;
    }
    return res;
}

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

    using F1 = function<sum_t(sum_t, sum_t)>;
    using F2 = function<sum_t(sum_t, key_t)>;

    vector<vector<Edge>> g;
    vector<sum_t> subdp, dp;
    const sum_t ident;
    const F1 f1;
    const F2 f2;

    ReRooting(int V, const F1 f1, const F2 f2, const sum_t &ident)
        : g(V), f1(f1), f2(f2), ident(ident), subdp(V, ident), dp(V, ident) {}

    void add_edge(int u, int v, const key_t &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 key_t &d, const key_t &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] = f1(subdp[idx], f2(subdp[e.to], e.data));
        }
    }

    void dfs_all(int idx, int par, const sum_t &top) {
        sum_t buff{ident};
        for(int i = 0; i < (int) g[idx].size(); i++) {
        auto &e = g[idx][i];
        e.ndp = buff;
        e.dp = f2(par == e.to ? top : subdp[e.to], e.data);
        buff = f1(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, f1(e.ndp, buff));
        e.ndp = f1(e.ndp, buff);
        buff = f1(buff, e.dp);
        }
    }

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

ll N;
vector<ll> tmp(4);

// 1,2番目に大きいものを残す
pll f1(pll a, pll b) {
    tmp[0] = a.first;
    tmp[1] = a.second;
    tmp[2] = b.first;
    tmp[3] = b.second;
    sort(btoe(tmp));
    return mkp(tmp[3], tmp[2]);
}

pll f2(pll a, ll x) {
    return mkp(a.first + x, 0);
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    cin >> N;
    ReRooting<pll, ll> rr(N, f1, f2, mkp(0, 0));
    ll a, b, c;
    rep(i, 0, N-1) {
        cin >> a >> b >> c;
        rr.add_edge(a, b, c);
    }
    vector<pll> res = rr.build();
    ll ans = 0;
    for (pll p : res) {
        chmax(ans, p.first + p.second);
    }
    print(ans);
    return 0;
}



Measured memory_bytes: 44212