#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
#define X first
#define Y second
#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 dp00[MXN], dp01[MXN], dp10[MXN], dp11[MXN];
vector<pii> g[MXN];
void dfs(int v, int p=0) {
for(auto [u, w] : g[v])
if(u != p)
dfs(u, v);
dp01[v] = dp10[v] = dp11[v] = -INF;
ll mx1=-INF, mx2=-INF;
for(auto [u, w] : g[v])
if(u!=p) {
ll val = max({dp00[u], dp11[u], dp10[u]+w});
dp00[v] += val;
val = max(dp00[u],dp11[u])+w-val;
if(val>=mx1) swap(val, mx1);
if(val>=mx2) swap(val, mx2);
}
for(auto [u, w] : g[v])
if(u!=p) {
ll val = max({dp00[u], dp11[u], dp10[u]+w});
maxs(dp11[v], dp00[v]-val+dp01[u]+w);
maxs(dp01[v], dp00[v]-val+max(dp00[u], dp11[u])+w);
maxs(dp10[v], dp00[v]-val+dp00[u]+w);
maxs(dp11[v], dp00[v]-val+w
+ (max(dp00[u], dp11[u])+w-val==mx1 ? mx2 : mx1));
}
}
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 << max(dp00[1], dp11[1]) << '\n';
return 0;
}
