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

struct Edge { int to; ll w; };
vector<vector<Edge>> adj;
ll max_dist;
int max_v;

void dfs(int v, int p, ll d) {
    if (d > max_dist) max_dist = d, max_v = v;
    for (auto& e : adj[v])
        if (e.to != p) dfs(e.to, v, d + e.w);
}

int main() {
    int N;
    cin >> N;
    adj.resize(N + 1);
    for (int i = 0; i < N - 1; ++i) {
        int u, v;
        ll w;
        cin >> u >> v >> w;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }
    max_dist = -1e18;
    dfs(1, -1, 0);
    int start = max_v;
    max_dist = -1e18;
    dfs(start, -1, 0);
    cout << max_dist << endl;
    return 0;
}