#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10, inf = 1e9 + 5;
int dp[N][2], dpU[N][2], par[N], mx[N], E[N][3], MX1[N], MX2[N];
vector <int> g[N];
inline int adj(int v, int i) {return (v^E[i][0]^E[i][1]);}
void dfs(int v)
{
for (int i : g[v]) if (adj(v, i) != par[v]) {
par[adj(v, i)] = v;
dfs(adj(v, i));
mx[adj(v, i)] = max(dp[adj(v, i)][1] + E[i][2], dp[adj(v, i)][0]);
dp[v][0] += mx[adj(v, i)];
}
for (int i : g[v]) if (adj(v, i) != par[v]) {
if (dp[adj(v, i)][0] - mx[adj(v, i)] + E[i][2] > MX1[v])
MX2[v] = MX1[v], MX1[v] = dp[adj(v, i)][0] - mx[adj(v, i)] + E[i][2];
else if (dp[adj(v, i)][0] - mx[adj(v, i)] + E[i][2] > MX2[v])
MX2[v] = dp[adj(v, i)][0] - mx[adj(v, i)] + E[i][2];
dp[v][1] = max(dp[v][1], dp[v][0] - mx[adj(v, i)] + dp[adj(v, i)][0] + E[i][2]);
}
}
void dfsUp(int v, int w = 0)
{
int p = par[v];
if (p != 0) {
int x = dpU[p][0] + dp[p][0] - mx[v] + w;
dpU[v][0] = x - w, dpU[v][1] = x;;
if (MX1[p] != dp[v][0] - mx[v] + w) dpU[v][0] = max(dpU[v][0], MX1[p] + x);
else dpU[v][0] = max(dpU[v][0], MX2[p] + x);
dpU[v][0] = max(dpU[v][0], dpU[p][1] - dpU[p][0] + x);
}
for (int i : g[v]) if (adj(v, i) != p) dfsUp(adj(v, i), E[i][2]);
}
int32_t main()
{
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
int n; cin >> n;
for (int i = 0; i < n - 1; i++) {
cin >> E[i][0] >> E[i][1] >> E[i][2];
g[E[i][0]].push_back(i);
g[E[i][1]].push_back(i);
}
for (int i = 1; i <= n; i++) MX1[i] = MX2[i] = dp[i][1] = dpU[i][1] = -inf;
dfs(1), dfsUp(1);
int ans = 0;
for (int i = 1; i <= n; i++) ans = max(ans, dp[i][0] + dpU[i][0]);
cout << ans << "\n";
return 0;
}
