#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
const int N = 200'010;
vector<pii> A[N];
int n;
tuple<int,int,int> dfs(int v, int p, int w)
{
int sum = 0, sum1 = 0;
vector<int> vec; // 2 - 0 + w
for (auto [u, e] : A[v]) {
if (u == p)
continue;
auto [x, y, z] = dfs(u, v, e);
vec.push_back(z - x + e);
sum += x;
sum1 += y;
}
sort(vec.rbegin(), vec.rend());
int x = 0, y = 0, z = 0;
if (vec.size() >= 1 && p >= 0)
x = sum + w + vec[0];
if (vec.size() >= 2)
z = sum + vec[0] + vec[1];
y = max(x, z);
x = max(x, sum);
y = max(y, sum1);
z = max(z, sum1);
return {x, y, z};
}
int main()
{
cin.tie(0) -> sync_with_stdio(false);
cin >> n;
Loop (i,1,n) {
int v, u, w;
cin >> v >> u >> w;
--v; --u;
A[v].push_back({u, w});
A[u].push_back({v, w});
}
cout << get<1>(dfs(0, -1, 0)) << '\n';
}
