#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
const int MAX = 200005;
typedef pair<int, int> pii;
vector<pii> g[MAX];
int dp[MAX][2][2];
int max(int a, int b, int c) { return max(max(a, b), c); }
int max(int a, int b, int c, int d) { return max(max(a, b), max(c, d)); }
void dfs(int u, int p=-1, int len=-1) {
for (pii i : g[u]) {
if (i.f == p) { continue; }
dfs(i.f, u, i.s);
}
int sum = 0, sum2 = 0;
vector<pii> val0, val1;
for (pii i : g[u]) {
if (i.f == p) { continue; }
sum += max(dp[i.f][0][0], dp[i.f][1][0]);
val0.push_back({max(dp[i.f][0][0], dp[i.f][1][0]) - dp[i.f][0][0] - i.s, i.f});
val1.push_back({max(dp[i.f][0][0], dp[i.f][1][0]) - dp[i.f][0][1] - i.s, i.f});
}
sort(val0.begin(), val0.end());
sort(val1.begin(), val1.end());
for (int i=0; i<min(2, (int)val0.size()); i++) {
for (int j=0; j<min(2, (int)val1.size()); j++) {
if (val0[i].s != val1[j].s) {
dp[u][0][1] = max(dp[u][0][1], sum - val0[i].f - val1[j].f);
}
}
}
if (val0.size() >= 2) {
dp[u][0][1] = max(dp[u][0][1], sum - val0[0].f - val0[1].f);
}
if (p != -1) {
for (pii i : g[u]) {
if (i.f == p) { continue; }
dp[u][1][0] = max(dp[u][1][0], len + sum - max(dp[i.f][0][0], dp[i.f][1][0]) + dp[i.f][0][0] + i.s);
dp[u][1][1] = max(dp[u][1][1], len + sum - max(dp[i.f][0][0], dp[i.f][1][0]) + dp[i.f][0][1] + i.s);
}
}
dp[u][0][0] = sum;
for (pii i : g[u]) {
if (i.f == p) { continue; }
dp[u][0][1] = max(dp[u][0][1], sum - max(dp[i.f][0][0], dp[i.f][1][0]) + max(dp[i.f][0][1], dp[i.f][1][1]));
}
// cout << u << " " << dp[u][0][0] << " " << dp[u][0][1] << " " << dp[u][1][0] << " " << dp[u][1][1] << endl;
}
int main() {
// freopen("a.in", "r", stdin);
// freopen("a.out", "w", stdout);
int n; scanf("%d", &n);
for (int i=0; i<n-1; i++) {
int u, v, w; scanf("%d %d %d", &u, &v, &w);
g[u].push_back({v, w});
g[v].push_back({u, w});
}
dfs(1);
printf("%d\n", max(dp[1][0][0], dp[1][0][1], dp[1][1][0], dp[1][1][1]));
}
