#include <stdio.h>
#include <vector>
#include <algorithm>
#define N 200001
#define INF 999999999999999999
using namespace std;
int n;
long long dp[N][4];
bool check[N][4];
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;
long long _MAX1 = -INF, _MAX2 = -INF;
long long __MAX1 = -INF, __MAX2 = -INF;
int k1 = 0, k2 = 0;
if (!check[x][y]) {
check[x][y] = true;
if (y == 1) {
for (auto i : r[x])
if (i.first != up) {
long long Push = max2(f(i.first, 3, x) + i.second, f(i.first, 2, 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;
long long sum = 0;
MAX1 = 0;
for (auto i : r[x])
if (i.first != up) {
long long Push = max2(f(i.first, 3, x) + i.second, f(i.first, 2, x));
long long _temp = max2(f(i.first, 1, x) + i.second, f(i.first, 0, x)) - Push;
long long temp = i.second + f(i.first, 2, x) - Push;
if (MAX1 < temp) MAX2 = MAX1, MAX1 = temp, k1 = i.first;
else if (MAX2 < temp) MAX2 = temp;
if (_MAX1 < _temp) _MAX2 = _MAX1, _MAX1 = _temp, k2 = i.first;
else if (_MAX2 < _temp) _MAX2 = _temp;
sum += Push;
}
if (k1 != k2) dp[x][y] = max2(dp[x][y], sum + MAX1 + _MAX1);
else dp[x][y] = max2(dp[x][y], max2(sum + MAX1 + _MAX2, sum + MAX2 + _MAX2));
}
else if (y == 3) {
for (auto i : r[x])
if (i.first != up) {
long long Push = max2(f(i.first, 3, x) + i.second, f(i.first, 2, x));
long long temp = i.second + f(i.first, 2, x) - Push;
if (MAX1 < temp) MAX2 = MAX1, MAX1 = temp;
else if (MAX2 < temp) MAX2 = temp;
dp[x][y] += Push;
}
dp[x][y] += MAX1;
}
else if (y == 0) {
for (auto i : r[x])
if (i.first != up) {
long long Push = max2(f(i.first, 3, x) + i.second, f(i.first, 2, x));
long long temp = i.second + f(i.first, 0, x) - Push;
long long _temp = i.second + f(i.first, 2, x) - Push;
long long __temp = max2(f(i.first, 1, x) + i.second, f(i.first, 0, x)) - Push;
if (__MAX1 < __temp) __MAX1 = __temp;
if (MAX1 < temp) MAX2 = MAX1, MAX1 = temp, k1 = i.first;
else if (MAX2 < temp) MAX2 = temp;
if (_MAX1 < _temp) _MAX2 = _MAX1, _MAX1 = _temp, k2 = i.first;
else if (_MAX2 < _temp) _MAX2 = _temp;
dp[x][y] += Push;
}
if (k1 != k2) dp[x][y] = max2(dp[x][y]+max2(0,__MAX1), dp[x][y] + MAX1 + _MAX1);
else dp[x][y] = max2(dp[x][y]+max2(0,__MAX1), max2(dp[x][y] + MAX1 + _MAX2, dp[x][y] + MAX2 + _MAX1));
}
else if (y == 2) {
for (auto i : r[x])
if (i.first != up) {
long long Push = max2(f(i.first, 3, x) + i.second, f(i.first, 2, x));
dp[x][y] += Push;
}
}
} return dp[x][y];
}
int main() {
// freopen("input.txt", "r", stdin);
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("> %d", f(6, 3, 1));
printf("%lld", f(1, 0, 0));
}
