#include <stdio.h>
#include <vector>
#include <algorithm>
#define N 200001
#define INF 999999999999999999
using namespace std;
int n;
long long dp[N][2];
bool check[N][2];
vector<pair<int, long long> > r[N];
long long max2(long long x, long long y) { return x > y ? x : y; }
long long f(int x, int y, int up) {
long long MAX1 = -INF, MAX2 = -INF;
if (!check[x][y]) {
check[x][y] = true;
if (y) {
for (auto i : r[x])
if (i.first != up) {
long long Push = max2(f(i.first, 1, x) + i.second, f(i.first, 0, x));
long long temp = i.second + f(i.first, 0, x) - Push;
if (MAX1 < temp) MAX1 = temp;
dp[x][y] += Push;
}
dp[x][y] += MAX1;
}
else {
for (auto i : r[x])
if (i.first != up) {
long long Push = max2(f(i.first, 1, x) + i.second, f(i.first, 0, x));
long long temp = i.second + f(i.first, 0, x) - Push;
if (MAX1 < temp) MAX2 = MAX1, MAX1 = temp;
else if (MAX2 < temp) MAX2 = temp;
dp[x][y] += Push;
}
dp[x][y] += max2(0, MAX1 + MAX2);
}
} return dp[x][y];
}
int main() {
int x, y, z;
scanf("%d", &n);
for (int i = 1; i < n; i++) {
scanf("%d %d %d", &x, &y, &z);
r[x].push_back({ y,(long long)z }), r[y].push_back({ x,(long long)z });
}
printf("%lld", f(1, 0, 0));
}
