#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
const int MAXN = 2e5;
int n;
int dp[MAXN][2]; // open, closed
vector<pii> edges[MAXN];
int par_val[MAXN];
struct comp {
bool operator()(int &a, int &b) {
return a > b;
}
} comp;
void dfs(int cur = 0, int p = -1) {
int o_sum = 0;
vector<int> diffs;
for (pii edge: edges[cur]) {
int next = edge.first;
if (next == p) continue;
par_val[next] = edge.second;
dfs(next, cur);
o_sum += dp[next][0];
diffs.push_back(edge.second+dp[next][1]-dp[next][0]);
}
sort(diffs.begin(), diffs.end(), comp);
int ex = 0;
if (diffs.size() >= 2) ex = diffs[0]+diffs[1];
dp[cur][1] = max(ex, 0)+o_sum;
if (diffs.size() == 1 || (diffs.size() >= 2 && par_val[cur] > diffs[1])) ex = diffs[0]+par_val[cur];
dp[cur][0] = max(ex, 0)+o_sum;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
cin >> n;
for (int i = 0; i < n-1; i++) {
int x, y, w;
cin >> x >> y >> w; x--; y--;
edges[x].push_back(pii(y, w));
edges[y].push_back(pii(x, w));
}
dfs();
cout << dp[0][1] << "\n";
}
