#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int N = 200100;
vector <pair<int, int> > g[N];
ll dp[4][N];
int n;
void dfs(int v, int p, int lenTo){
ll sum = 0;
ll mx1 = -1e15, mx2 = -1e15, mx3 = -1e15;
for (int i = 0; i < g[v].size(); i++){
int to = g[v][i].first, len = g[v][i].second;
if (to == p)
continue;
dfs(to, v, len);
sum += max(dp[0][to], dp[1][to]);
mx1 = max(mx1, max(dp[2][to], dp[3][to]) - max(dp[0][to], dp[1][to]));
mx2 = max(mx2, dp[0][to] + len - max(dp[0][to], dp[1][to]));
mx3 = max(mx3, dp[2][to] + len - max(dp[0][to], dp[1][to]));
}
dp[0][v] = max(0ll, sum);
dp[2][v] = max(0ll, sum + mx1);
if (v != 1){
dp[1][v] = max(0ll, sum + mx2 + lenTo);
dp[3][v] = max(0ll, sum + mx3 + lenTo);
}
mx1 = mx2 = -1e15;
for (int i = 0; i < g[v].size(); i++){
int to = g[v][i].first, len = g[v][i].second;
if (to == p)
continue;
dp[2][v] = max(dp[2][v], sum + mx1 + max(dp[0][to], dp[2][to]) + len - max(dp[0][to], dp[1][to]) );
dp[2][v] = max(dp[2][v], sum + mx2 + dp[0][to] + len - max(dp[0][to], dp[1][to]));
mx1 = max(mx1, dp[0][to] + len - max(dp[0][to], dp[1][to]));
mx2 = max(mx2, dp[2][to] + len - max(dp[0][to], dp[1][to]));
}
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin >> n;
for (int i = 2; i <= n; i++){
int u, v, c;
cin >> u >> v >> c;
g[u].push_back({v, c});
g[v].push_back({u, c});
}
dfs(1, 0, 0);
cout << max({dp[0][1], dp[1][1], dp[2][1], dp[3][1]});
}
/**
*/
