#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 1;
int n;
vector<pair<int,int> > adj[N];
int a[N][4];
void dfs(int u,int p)
{
a[u][1] = -2e9;
a[u][3] = -2e9;
int m3 = -2e9,m21 = -2e9,m22 = -2e9,m01 = -2e9,m02 = -2e9,v2,v0;
for(auto [d,v] : adj[u]) if(v!=p)
{
dfs(v,u);
int each = max(a[v][0],a[v][2]),ez = a[v][1]+d;
a[u][0]+=max(each,ez);
a[u][1] = max(a[u][1],a[v][0]+d-max(each,ez));
m3 = max(m3,a[v][3]+d-max(each,ez));
if(a[v][2]+d-max(each,ez)>m21) m22 = m21,m21 = a[v][2]+d-max(each,ez),v2 = v;
else if(a[v][2]+d-max(each,ez)>m22) m22 = a[v][2]+d-max(each,ez);
if(a[v][0]+d-max(each,ez)>m01) m02 = m01,m01 = a[v][0]+d-max(each,ez),v0 = v;
else if(a[v][0]+d-max(each,ez)>m02) m02 = a[v][0]+d-max(each,ez);
a[u][3] = max(a[u][3],a[v][2]+d-max(each,ez));
}
a[u][1]+=a[u][0];
a[u][3]+=a[u][0];
if(m01!=-2e9 and m02!=-2e9) a[u][2] = max(a[u][2],m01+m02);
if(m01!=-2e9 and m21!=-2e9 and v2!=v0) a[u][2] = max(a[u][2],m01+m21);
if(m02!=-2e9 and m21!=-2e9) a[u][2] = max(a[u][2],m02+m21);
if(m01!=-2e9 and m22!=-2e9) a[u][2] = max(a[u][2],m01+m22);
a[u][2] = max(a[u][2],m3);
a[u][2]+=a[u][0];
/*
if(u==1)
{
cout << m01 << ' ' << m02 << ' ' << m21 << ' ' << m22 << endl;
}
cout << u << ' ' << lft << endl;
for(int i = 0;i < 4;i++) cout << a[u][i] << ' ';
cout << endl;
*/
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n;
for(int i = 0;i < n-1;i++)
{
int a,b,d;
cin >> a >> b >> d;
adj[a].push_back({d,b});
adj[b].push_back({d,a});
}
dfs(1,0);
cout << max(a[1][0],a[1][2]);
}
