#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int nx=2e5+5;
ll n, u, v, w, dp[nx][2][2];
vector<pair<ll, ll>> d[nx];
void dfs(int u, int p, ll pw)
{
ll sm=0, mx=-1e18;
pair<ll, ll> mx1={-1e18, 0}, smx1={-1e18, 0}, mx2={-1e18, 0}, smx2={-1e18, 0};
for (auto [v, w]:d[u])
{
if (v==p) continue;
dfs(v, u, w);
int cur=max(dp[v][1][0], dp[v][0][0]);
sm+=cur;
mx=max(mx, max(dp[v][0][1], dp[v][1][1])-cur);
int vl1=max(dp[v][0][0], dp[v][0][1])-cur+w;
if (vl1>mx1.first) swap(mx1, smx1), mx1={vl1, v};
else if (vl1>smx1.first) smx1={vl1, v};
int vl2=dp[v][0][0]-cur+w;
if (vl2>mx2.first) swap(mx2, smx2), mx2={vl2, v};
else if (vl2>smx2.first) smx2={vl2, v};
}
dp[u][0][0]=sm;
dp[u][0][1]=max(sm, sm+mx);
if (mx1.second==mx2.second) dp[u][0][1]=max(dp[u][0][1], sm+max(mx1.first+smx2.first, smx1.first+mx2.first));
else dp[u][0][1]=max(dp[u][0][1], sm+mx1.first+mx2.first);
dp[u][1][0]=max(sm, sm+mx2.first+pw);
dp[u][1][1]=max(sm, sm+mx1.first+pw);
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin>>n;
for (int i=1; i<n; i++) cin>>u>>v>>w, d[u].push_back({v, w}), d[v].push_back({u, w});
dfs(1, 1, 0);
cout<<max({dp[1][0][0], dp[1][0][1]});
}
