#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define FORU(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define IOS cin.tie(0)->sync_with_stdio(false);
#define PROB "APIO14_beads"
void Fi(){
if(fopen(PROB".inp", "r")){
freopen(PROB".inp", "r", stdin);
freopen(PROB".out", "w", stdout);
}
}
const int N = 2e5 + 1;
const ll INF = 1e15;
int n;
ll dp[2][N];
using pi = pair<int, int>;
vector<pi> adj[N];
int tc[2][N];
ll f[2][N], dif[2][N];
ll ans;
void dfs1(int u, int p){
dif[0][u] = dif[1][u] = -INF;
for(auto [w, v]: adj[u]) if(v != p){
dfs1(v, u);
f[0][u] += max(f[0][v], f[1][v] + w);
ll diftmp = (f[0][v] + w) - max(f[0][v], f[1][v] + w);
if(dif[0][u] < diftmp){
dif[1][u] = dif[0][u];
tc[1][u] = tc[0][u];
dif[0][u] = diftmp;
tc[0][u] = v;
} else if(dif[1][u] < diftmp){
dif[1][u] = diftmp;
tc[1][u] = v;
}
}
f[1][u] = f[0][u] + dif[0][u];
// cout << u << " " << f[0][u] << " " << f[1][u] << "\n";
// cout << dif[0][u] << " " << dif[1][u] << "\n\n";
}
void dfs2(int u, int p, ll wei, ll down[2]){
ll tot = f[0][u] + max(down[0], down[1] + wei);
ll diftmp = (down[0] + wei) - max(down[0], down[1] + wei);
ans = max(ans, tot);
// cout << u << " " << down[0] << " " << down[1] << " " << tot << " " << diftmp << "\n";
for(auto [w, v]: adj[u]) if(v != p){
ll dwn[2];
dwn[0] = tot - max(f[0][v], f[1][v] + w);
if(v != tc[0][u]){
dwn[1] = dwn[0] + max(dif[0][u], diftmp);
} else{
dwn[1] = dwn[0] + max(dif[1][u], diftmp);
}
dfs2(v, u, w, dwn);
}
}
int main(){
IOS;
Fi();
cin >> n;
FOR(i, 1, n){
int u, v, w;
cin >> u >> v >> w;
adj[u].eb(w, v);
adj[v].eb(w, u);
}
dfs1(1, -1);
ll down[2] = {0, -INF};
dfs2(1, -1, -INF, down);
cout << ans;
return 0;
}
