#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 2e5 + 10;
const int inf = 1e9;
int dp[maxn], pd[maxn];
vector<pair<int, int> > t[maxn];
pair<int,int> merge(pair<int,int> twomax, int k){
if (k > twomax.second)
twomax.second = k;
if (twomax.first < twomax.second)
swap(twomax.first, twomax.second);
return twomax;
}
void dfs(int v, int par = -1){
int sum = 0;
pair<int,int> twomax = {-inf, -inf};
for (auto edge : t[v]){
int u = edge.first, c = edge.second;
if (u != par){
dfs(u, v);
ll mx = max(dp[u], pd[u] + c);
sum += mx;
twomax = merge(twomax, dp[u] + c - mx);
}
}
int extra = max(0, twomax.first + twomax.second);
dp[v] = sum + extra;
pd[v] = sum + twomax.first;
}
int main(){
ios_base::sync_with_stdio (false);
int n;
cin >> n;
for (int i = 1; i <= n - 1; i++){
int v, u, c;
cin >> v >> u >> c;
t[v].push_back({u, c});
t[u].push_back({v, c});
}
dfs(1);
cout << dp[1] << endl;
}
