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

const ll INF = (ll)1e18;
int N;
vector<vector<pair<int,ll>>> adj;
ll ans = -INF;
vector<bool> seen;

ll dfs(int v, int par){
    vector<ll> child_vals;
    for(auto [u, w] : adj[v]){
        if(u == par) continue;
        ll sub = dfs(u, v) + w;
        child_vals.push_back(sub);
    }
    sort(child_vals.rbegin(), child_vals.rend());
    ll best_down = child_vals.empty() ? 0 : child_vals[0];
    ans = max(ans, best_down);
    if(child_vals.size() >= 2){
        ans = max(ans, child_vals[0] + child_vals[1]);
    }
    return best_down;
}

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

    cin >> N;
    adj.assign(N+1, {});
    for(int i = 1; i < N; i++){
        int u, v; ll w;
        cin >> u >> v >> w;
        adj[u].emplace_back(v, w);
        adj[v].emplace_back(u, w);
    }
    dfs(1, -1);
    cout << ans << "\n";
    return 0;
}