#include <bits/stdc++.h>
using namespace std;
#define int long long
const int inf = 1e18;
vector<vector<int>> dp;
vector<vector<pair<int, int>>> adj;
void dfs(int u, int p) {
int mx0=0, mx1=0;
pair<int, int> mxb[2]={{-inf, 0}, {-inf, 0}};
pair<int, int> mxr[2]={{-inf, 0}, {-inf, 0}};
for (auto& [v, w] : adj[u]) {
if (v==p) continue;
dfs(v, u);
int val=max(dp[v][1], dp[v][2]+w);
dp[u][0]+=val;
dp[u][1]+=val;
dp[u][2]+=val;
dp[u][3]+=val;
mx0=max(mx0, max(dp[v][0], dp[v][3]+w)-val);
mxr[1] = max(mxr[1], {dp[v][1]+w-val, v});
mxb[1] = max(mxb[1], {dp[v][0]+w-val, v});
if (mxr[0] < mxr[1]) swap(mxr[0], mxr[1]);
if (mxb[0] < mxb[1]) swap(mxb[0], mxb[1]);
}
if (mxr[0].second != mxb[0].second) mx1=mxr[0].first+mxb[0].first;
else mx1 = max(mxr[0].first + mxb[1].first, mxr[1].first + mxb[0].first);
dp[u][0]+=max(mx1, mx0);
dp[u][2]+=mxr[0].first;
dp[u][3]+=mxb[0].first;
}
signed main() {
cin.tie(0)->sync_with_stdio(false);
int n;
cin >> n;
adj.assign(n+1, vector<pair<int, int>>());
for (int i = 1; i < n; ++i) {
int a, b, c;
cin >> a >> b >> c;
adj[a].push_back({b, c});
adj[b].push_back({a, c});
}
dp.assign(n+1, vector<int>(4, 0));
dfs(1, 1);
cout << max(dp[1][0], dp[1][1]) << '\n';
return 0;
}
