#include <iostream>
#include <vector>
#define X first
#define Y second
#define MP make_pair
#define ll long long
using namespace std;
const int N = 1e5 + 12;
const int INF = 1e9;
int n, dp[2][N], ans;
vector< pair<int, int> > g[N];
void dfs(int v, int pr){
dp[0][v] = -INF;
for(pair<int, int> tmp: g[v]){
int to = tmp.X, cost = tmp.Y;
if(to != pr){
dfs(to, v);
dp[1][v] += max(dp[1][to], dp[0][to] + cost);
}
}
int sum = dp[1][v], c1 = -INF, c2 = -INF;
for(pair<int, int> tmp: g[v]){
int to = tmp.X, cost = tmp.Y;
if(to != pr){
int dt = cost;
if(dp[1][to] < dp[0][to] + cost)
dt = dp[1][to] - dp[0][to];
if(c1 < dt)
c2 = c1, c1 = dt;
else if(c2 < dt)
c2 = dt;
}
}
if(c1 != -INF)
dp[0][v] = sum + c1;
if(c2 != -INF)
dp[1][v] = max(dp[1][v], sum + c2 + c1);
ans = max(ans, dp[1][v]);
}
int main () {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
cin >> n;
for(int i = 1, x, y, z;i < n;i++){
cin >> x >> y >> z;
g[x].push_back(MP(y, z));
g[y].push_back(MP(x, z));
}
dfs(1, 1);
//cerr << dp[0][6] << "\n";
cout << ans;
}
