#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 5;
const long long inf = 1e15;
vector<pair<int, int>> graf[maxn];
long long dp[2][maxn], ans;
void dfs(int x, int p) {
dp[0][x] = 0; dp[1][x] = -inf;
for (auto u : graf[x]) if (u.first != p) {
dfs(u.first, x);
dp[0][x] += max(dp[1][u.first] + u.second, dp[0][u.first]);
}
for (auto u : graf[x]) if (u.first != p) {
long long t = max(dp[1][u.first] + u.second, dp[0][u.first]);
dp[1][x] = max(dp[1][x], dp[0][x] - t + dp[0][u.first] + u.second);
}
}
void dfsans(int x, int p, long long f, long long t0, long long t1) {
long long k0 = dp[0][x] + max(t1 + f, t0);
ans = max(ans, k0);
pair<long long, int> p1 = make_pair(-inf, -1), p2 = make_pair(-inf, -1);
for (auto u : graf[x]) if (u.first != p) {
long long k = max(dp[1][u.first] + u.second, dp[0][u.first]);
long long c = -k + dp[0][u.first] + u.second;
pair<long long, int> pt = make_pair(c, u.first);
if (pt > p1) p2 = p1, p1 = pt;
else if (pt > p2) p2 = pt;
}
for (auto u : graf[x]) if (u.first != p) {
long long z0 = k0 - max(dp[1][u.first] + u.second, dp[0][u.first]);
long long z1 = z0 - max(t1 + f, t0) + t0 + f;
z1 = max(z1, z0 + (p1.second == u.first ? p2.first : p1.first));
dfsans(u.first, x, u.second, z0, z1);
}
}
int main() {
int n; scanf("%d", &n);
for (int i = 0; i < n - 1; ++i) {
int a, b, c; scanf("%d %d %d", &a, &b, &c);
graf[a].emplace_back(b, c);
graf[b].emplace_back(a, c);
}
dfs(1, 0);
ans = -inf;
dfsans(1, 0, -inf, 0, -inf);
printf("%lld%c\n", ans, (char)(13));
return 0;
}
