#include <bits/stdc++.h>
using namespace std;
int ans[200000][4];
bool vis[200000];
vector<vector<pair<int,int>>> gr;
void dfs(int v)
{
vis[v] =true;
int mx = -2e9;
int mx2 = 0;
int mx3 = -2e9;
vector<pair<int,int>> q;
vector<pair<int,int>> q2;
int cans = 0;
for(int i = 0;i<gr[v].size();i++)
{
if(!vis[gr[v][i].first])
{
dfs(gr[v][i].first);
ans[v][0] += ans[gr[v][i].first][1];
ans[v][1] += ans[gr[v][i].first][1];
mx = max(mx,gr[v][i].second+ans[gr[v][i].first][0]-ans[gr[v][i].first][1]);
mx2 = max(mx2,ans[gr[v][i].first][3] - ans[gr[v][i].first][1]);
ans[v][2] += ans[gr[v][i].first][1];
q.push_back({ans[gr[v][i].first][2]-ans[gr[v][i].first][1]+gr[v][i].second,i});
q2.push_back({ans[gr[v][i].first][0]-ans[gr[v][i].first][1]+gr[v][i].second,i});
cans+=ans[gr[v][i].first][1];
mx3 = max(mx3,ans[gr[v][i].first][2]-ans[gr[v][i].first][1]+gr[v][i].second);
}
else
{
ans[v][1] += gr[v][i].second;
ans[v][3] += gr[v][i].second;
}
}
ans[v][1] += mx;
ans[v][2] += mx2;
if(q.size() > 1)
{
sort(q.begin(),q.end());
reverse(q.begin(),q.end());
sort(q2.begin(),q2.end());
reverse(q2.begin(),q2.end());
if(q[0].second != q2[0].second)
{
ans[v][2] = max(ans[v][2],cans+q[0].first+q2[0].first);
}
else
{
ans[v][2] = max(ans[v][2],max(cans+q[0].first+q2[1].first,cans+q[1].first+q2[0].first));
}
}
ans[v][3] += mx3+cans;
ans[v][3] = max(ans[v][3],ans[v][2]);
ans[v][1] = max(ans[v][1],ans[v][0]);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cerr.tie(0);
int n;
cin>>n;
gr.resize(n);
for(int i = 0;i<n-1;i++)
{
int a,b,c;
cin>>a>>b>>c;
a--;b--;
gr[a].push_back({b,c});
gr[b].push_back({a,c});
}
dfs(0);
cout<<ans[0][2];
}
