#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 1;
int n;
vector<pair<int,int> > adj[N];
int dp[N][6];
int mxx(int a,int b,int c,int d){ return max(max(a,d),max(b,c)); }
void dfs(int u,int p)
{
int all = 0,mx = INT_MIN,mx2 = INT_MIN,mxc = INT_MIN,cn = 0;
dp[u][1] = INT_MIN,dp[u][2] = INT_MIN,dp[u][4] = INT_MIN,dp[u][5] = INT_MIN;
for(auto [d,v] : adj[u]) if(v!=p)
{
dfs(v,u);
int each = mxx(dp[v][0],dp[v][2],dp[v][3],dp[v][4]);
all+=each,cn+=max(each,d+dp[v][1]);
dp[u][1] = max(dp[u][1],d+max(dp[v][0],dp[v][2])-max(each,d+dp[v][1]));
int tmp = d+max(dp[v][0],dp[v][2])-max(each,d+dp[v][1]);
if(tmp>mx) mx2 = mx,mx = tmp;
else if(tmp>mx2) mx2 = tmp;
mxc = max(mxc,d+max(dp[v][3],dp[v][4])-max(each,d+dp[v][1]));
dp[u][4] = max(dp[u][4],d+dp[v][5]-max(each,d+dp[v][1]));
dp[u][5] = max(dp[u][5],d+max(dp[v][3],dp[v][4])-max(each,d+dp[v][1]));
}
dp[u][0] = all;
dp[u][1]+=cn;
dp[u][2] = cn;
if(mx==INT_MIN or (mx2==INT_MIN and mxc==INT_MIN)) dp[u][3] = INT_MIN;
else dp[u][3] = mx+max(mx2,mxc)+cn;
dp[u][4]+=cn;
dp[u][5]+=cn;
}
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 << mxx(dp[1][0],dp[1][2],dp[1][3],dp[1][4]);
}
