#include <bits/stdc++.h>
#include <atcoder/all>
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
namespace mp = boost::multiprecision;
using Bint = mp::cpp_int;
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n;
    cin >> n;
    vector<vector<P>> g(n);
    rep(i,n-1) {
        int u, v, w;
        cin >> u >> v >> w;
        --u;--v;
        g[u].emplace_back(v,w);
        g[v].emplace_back(u,w);
    }
    vector<ll> dp(n, -1e18);
    ll ans = 0;
    auto dfs = [&](auto dfs, int u, int p=-1) -> void {
        dp[u] = 0;
        vector<ll> vs;
        vs.push_back(0);
        vs.push_back(0);
        for(auto [v, w] : g[u]) {
            if(v==p) continue;
            dfs(dfs, v, u);
            dp[u] = max(dp[u], dp[v]+w);
            vs.push_back(dp[v]+w);
        }
        sort(vs.rbegin(),vs.rend());
        ans = max(ans, vs[0] + vs[1]);
    };
    dfs(dfs, 0);
    dbg(dp);
    cout << ans << endl;
    return 0;
}