#include <bits/stdc++.h>
#define ft first
#define sd second
#define int long long
using namespace std;
typedef pair<int, int> pii;
const int MAXN = 200 * 1000 + 23;
/*
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/
struct chi {
int x = INT_MIN, y = INT_MIN;
void f(int z) {
if (x < z) {
y = x;
x = z;
} else y = max(y, z);
}
};
int n, dp[2 + 2][MAXN];
vector<pii> g[MAXN];
void dfs(int v, int p, int val) {
vector<pii> vec;
for (auto i : g[v]) if (i.ft != p) {
dfs(i.ft, v, i.sd);
vec.push_back(i);
}
if (vec.empty()) return;
int tmp = 0, tmx = INT_MIN;
for (auto i : vec) tmp += dp[1][i.ft];
dp[0][v] = dp[1][v] = tmp;
for (auto i : vec) if (tmx < i.sd + dp[0][i.ft] - dp[1][i.ft]) tmx = i.sd + dp[0][i.ft] - dp[1][i.ft];
dp[1][v] = max(tmp, tmp + tmx + val);
chi h;
for (auto i : vec) h.f(i.sd + dp[0][i.ft] - dp[1][i.ft]);
dp[0][v] = max(dp[0][v], tmp + h.x + h.y);
dp[1][v] = max(dp[1][v], tmp + h.x + h.y);
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr), cout.tie(nullptr);
cin >> n;
{
int a, b, c;
for (int i = 1; i < n; i++) {
cin >> a >> b >> c;
g[--a].push_back({--b, c}), g[b].push_back({a, c});
}
}
dfs(0, -1, INT_MIN);
cout << dp[1][0];
return 0;
}
