#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];
ll p0[MXN], p1[MXN], s0[MXN], s1[MXN];
vector<pii> g[MXN];
void dfs(int v, int p=0) {
vector<pii> ch;
for(auto [u, w] : g[v]) if(u != p)
dfs(u, v),
ch.pb(Mp(u,w));
int sz = SZ(ch);
dp01[v] = -INF; dp10[v] = -INF; dp11[v] = -INF;
for(auto [u, w] : ch)
dp00[v] += max(dp00[u], dp10[u]+w);
dp01[v] = dp00[v];
for(auto [u, w] : ch) {
ll val = dp00[v]-max(dp00[u], dp10[u]+w);
maxs(dp01[v], val+max(dp01[u], dp11[u]+w));
maxs(dp10[v], val+dp00[u]+w);
maxs(dp11[v], val+max(dp00[u],dp01[u])+w);
}
maxs(dp11[v], dp10[v]);
if(sz<=1) {
if(sz==0) {
dp00[v] = dp01[v] = 0;
dp10[v] = dp11[v] = -INF;
}
return;
}
fill(p0, p0+sz, 0);
fill(p1, p1+sz, 0);
fill(s0, s0+sz, 0);
fill(s1, s1+sz, 0);
for(int i=0; i<sz; i++) {
auto [u, w] = ch[i];
ll val = max(dp00[u], dp10[u]+w);
if(i==0) {
p0[i] += val;
p1[i] += dp00[u]+w;
}
else {
p0[i] = p0[i-1]; p1[i] = p1[i-1];
p0[i] += val;
p1[i] = max(p0[i-1]+dp00[u]+w, p1[i-1]+val);
}
}
for(int i=sz-1; i>=0; i--) {
auto [u, w] = ch[i];
ll val = max(dp00[u], dp10[u]+w);
if(i==sz-1) {
s0[i] += val;
s1[i] += dp00[u]+w;
}
else {
s0[i] = s0[i+1]; s1[i] = s1[i+1];
s0[i] += val;
s1[i] = max(s0[i+1]+dp00[u]+w, s1[i+1]+val);
}
}
for(int i=0; i<sz; i++) {
auto [u, w] = ch[i];
if(i==0)
maxs(dp01[v], dp01[u]+w+s1[i+1]);
else if(i==sz-1)
maxs(dp01[v], dp01[u]+w+p1[i-1]);
else
maxs(dp01[v], dp01[u]+w+max(p0[i-1]+s1[i+1], p1[i-1]+s0[i+1]));
}
}
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], dp01[1]) << '\n';
return 0;
}
