#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N=200010, INF=1e15;
int n, pw[N], dp[2][N], ep[2][N];
vector<pair<int, int>> adj[N];
void dfs(int curr, int prev) {
int mx1=-INF, mx2=-INF, sum=0, mx3=-INF, mx4=-INF, mx5=-INF;
vector<int> vec;
for(auto [next, w]:adj[curr]) if(next!=prev) {
pw[next]=w, dfs(next, curr);
dp[0][curr]+=max(dp[0][next], ep[0][next]);
ep[0][curr]+=max(dp[0][next], ep[0][next]);
if(dp[0][next]>=ep[0][next]) mx1=max(mx1, w);
else mx1=max(mx1, dp[0][next]+w-ep[0][next]);
ep[1][curr]+=max({dp[0][next], dp[1][next], ep[0][next], ep[1][next]});
if(max(dp[0][next], dp[1][next])>=ep[0][next]) mx2=max(mx2, w);
else mx2=max(mx2, max(dp[0][next], dp[1][next])+w-max(ep[0][next], ep[1][next]));
sum+=max(dp[0][next], ep[0][next]);
if(dp[0][next]>=ep[0][next]) {
if(mx3<w) mx4=mx3, mx3=w;
else if(mx4<w) mx4=w;
}
else {
if(mx3<dp[0][next]+w-ep[0][next]) mx4=mx3, mx3=dp[0][next]+w-ep[0][next];
else if(mx4<dp[0][next]+w-ep[0][next]) mx4=dp[0][next]+w-ep[0][next];
}
vec.push_back(mx3);
}
ep[0][curr]+=mx1+pw[curr], ep[1][curr]+=mx2+pw[curr];
dp[1][curr]=sum+mx3+mx4;
reverse(adj[curr].begin(), adj[curr].end());
int p=vec.size()-1;
for(auto [next, w]:adj[curr]) if(next!=prev) {
dp[1][curr]=max(dp[1][curr], sum-max(dp[0][next], ep[0][next])+dp[1][next]+w+max(mx5, p?vec[--p]:-INF));
}
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n;
for(int i=1; i<n; i++) {
int u, v, w; cin>>u>>v>>w;
adj[u].push_back({v, w}), adj[v].push_back({u, w});
}
fill(dp[1]+1, dp[1]+n+1, -INF);
dfs(1, 0);
cout<<max(dp[0][1], dp[1][1]);
return 0;
}
