#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 2e5 + 10;
const int inf = 1e8;
int dp[maxn], pd[maxn], DP[maxn], PD[maxn];
vector<pair<int, int> > t[maxn];
vector<int> parmax[maxn], revmax[maxn];
void DFS(int v, int par = -1, int weight = 0, int ord = 0){
if (par != -1){
int pdup = dp[par] + DP[par] - max(dp[v], pd[v] + weight);
int mx = -inf;
if (ord)
mx = max(mx, parmax[par][ord - 1]);
if (ord != t[par].size() - 1)
mx = max(mx, revmax[par][ord + 1]);
DP[v] = max(pdup, pdup + mx + weight);
PD[v] = pdup + weight;
// cout << "dfs down -> " << v << " -> " << DP[v] << " " << PD[v] << " pdup : " << pdup << endl;
}
for (int i = 0; i < t[v].size(); i++){
auto edge = t[v][i];
int u = edge.first, c = edge.second;
if (u != par){
parmax[v].push_back(dp[u] + c - max(dp[u], pd[u] + c));
revmax[v].push_back(dp[u] + c - max(dp[u], pd[u] + c));
}
else{
int pdup = dp[par] + DP[par] - max(dp[v], pd[v] + weight);
int mx = -inf;
if (ord)
mx = max(mx, parmax[par][ord - 1]);
if (ord != t[par].size() - 1)
mx = max(mx, revmax[par][ord + 1]);
DP[v] = max(pdup, pdup + mx + weight);
parmax[v].push_back(pdup + c - max(pdup, pdup + mx + c));
revmax[v].push_back(pdup + c - max(pdup, pdup + mx + c));
}
}
for (int i = 1; i < t[v].size(); i++)
parmax[v][i] = max(parmax[v][i], parmax[v][i - 1]);
for (int i = t[v].size() - 1; i >= 0; i--)
revmax[v][i] = max(revmax[v][i], revmax[v][i + 1]);
for (int i = 0; i < t[v].size(); i++){
auto edge = t[v][i];
int u = edge.first, c = edge.second;
if (u != par)
DFS(u, v, c, i);
}
}
void dfs(int v, int par = -1){
int mx = -inf;
dp[v] = 0;
for (int i = 0; i < t[v].size(); i++){
auto edge = t[v][i];
int u = edge.first, c = edge.second;
if (u != par){
dfs(u, v);
dp[v] += max(dp[u], pd[u] + c);
mx = max(mx, dp[u] + c - max(dp[u], pd[u] + c));
}
}
pd[v] = dp[v] + mx;
// cout << v << " -> " << dp[v] << " " << pd[v] << endl;
}
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);
DFS(1);
int answer = 0;
for (int v = 1; v <= n; v++){
answer = max(answer, dp[v] + DP[v]);
// cout << "# " << dp[v] << " " << DP[v] << endl;
}
cout << answer << endl;
}
