#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 3;
int n;
int dp[N][2][2];
typedef pair < int, int > ii;
vector < ii > adj[N];
void dfs(int i, int j)
{
dp[i][0][0] = 0;
dp[i][0][1] = 0;
//if (adj[i].size() == 2) dp[i][1][1] = 0;
for (ii cur : adj[i])
{
int u = cur.first;
int w = cur.second;
if (u == j) continue;
dfs(u, i);
dp[i][1][1] = max(dp[i][1][1] + max({dp[u][0][0], dp[u][0][1], dp[u][1][0] + w}),
dp[i][1][0] + max({dp[u][1][1], dp[u][0][0], dp[u][0][1]}) + w);
dp[i][1][0] = max(dp[i][1][0], dp[i][1][0] + max({dp[u][0][0], dp[u][0][1], dp[u][1][0] + w}));
dp[i][1][0] = max(dp[i][1][0], dp[i][0][0] + max({dp[u][1][1], dp[u][0][0], dp[u][0][1]}) + w);
dp[i][1][0] = max(dp[i][1][0], dp[i][0][1] + max({dp[u][1][1], dp[u][0][0], dp[u][0][1]}) + w);
dp[i][0][0] += max({dp[u][0][0], dp[u][1][1], dp[u][0][1]});
dp[i][0][1] += max({dp[u][1][1], dp[u][0][0], dp[u][0][1], dp[u][1][0] + w});
//if (i == 1) cout << u << " " << dp[i][0][0] << " " << dp[i][0][1] << '\n';
}
//if (i == 10) cout << i << " " << dp[i][0][0] << " " << dp[i][0][1] << " " << dp[i][1][0] << " " << dp[i][1][1] << '\n';
}
int main()
{
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//freopen("t.inp","r",stdin); freopen("t.out","w",stdout);
cin >> n;
for (int i = 1; i < n; i++)
{
int u, v, w;
cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
}
for (int i = 1; i <= n; i++)
dp[i][1][1] = dp[i][1][0] = -1e9,
dp[i][0][1] = dp[i][0][0] = -1e9;
dfs(1, 0);
// for (int i = 1; i <= n; i++)
// cout << i << " " << dp[i][0][0] << " " << dp[i][0][1] << " " << dp[i][1][0] << " " << dp[i][1][1] << '\n';
cout << max({dp[1][0][0], dp[1][0][1], dp[1][1][1]});
}
