#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
#define SZ(x) int(x.size())
#define pb push_back
#define all(x) x.begin(), x.end()
#define maxs(a, b) (a = max(a,b))
#define mins(a, b) (a = min(a,b))
#define Mp make_pair
#define mid ((l+r)>>1)
const int MXN = 2e5+1;
const int INF = 1e9;
int n;
ll dp[MXN][2];
vector<pii> g[MXN];
void insert(ll &mx1, ll &mx2, ll &mx3, ll x) {
if(x>=mx1) mx3=mx2, mx2=mx1, mx1=x;
else if(x>=mx2) mx3=mx2, mx2=x;
else if(x>=mx3) mx3=x;
}
// ll erase(ll mx1, ll mx2, ll mx3, ll x) {
// if(x==mx1) return mx2+mx3;
// if(x==mx2) return mx1+mx3;
// return mx1+mx2;
// }
void dfs(int v, int p=0) {
ll sum=0, mx1=-INF, mx2=-INF, mx3=-INF;
for(auto [u,w]: g[v])
if(u!=p) {
dfs(u, v);
ll val = max(dp[u][0], dp[u][1]+w);
sum += val;
insert(mx1, mx2, mx3, dp[u][0]+w-val);
}
dp[v][0] = sum + max(0ll, mx1+mx2);
dp[v][1] = sum + max(mx1, mx1 + mx2 + mx3);
}
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
cin >> n;
for(int i=0,u,v,w; i<n-1; i++) {
cin >> u >> v >> w;
g[u].pb(Mp(v,w));
g[v].pb(Mp(u,w));
}
dfs(1);
cout << dp[1][0] << '\n';
return 0;
}
