#include<bits/stdc++.h>
using namespace std;
#define f first
#define s second
typedef long long ll;
const int maxn = 2e5+5;
const int inf = 1e9;
ll dp[maxn][4];
// 1st mask: across edge
// 2nd mask: require upedge
int n;
vector<pair<int, int>> tree[maxn];
void dfs(int x, int p, int w){
if(x != 1 && tree[x].size() == 1)dp[x][1]=w;
else{
ll best[4], sum = 0;
for(int i = 0; i < 4; i++)best[i]=dp[x][i]=-inf;
// 00 : all 00 or one 01 + w
// 01: all 00 + w
// 10: one 10, one 01, all 00+w || one 11, all 00+w || one 11, one 01,all 00 || two 01, all 00 || one 10, all 00
// 11: (one 10, all 00 || one 11, one 01,all 00 || two 01, all 00)+w
for(auto v: tree[x]){
if(v.f == p)continue;
dfs(v.f, x, v.s);
ll base = dp[v.f][0];
sum+=base;
for(int i = 0; i< 4; i++)dp[v.f][i]-=base;
dp[x][2]=max(dp[x][2], best[2]+dp[v.f][1]+w);
dp[x][2] = max(dp[x][2], best[1] + dp[v.f][2]);
dp[x][2] = max(dp[x][2], best[1] + dp[v.f][3]);
dp[x][2] = max(dp[x][2], best[3] + dp[v.f][1]);
dp[x][2] = max(dp[x][2], best[1] + dp[v.f][1]);
dp[x][3] = max(dp[x][3], best[3] + dp[v.f][1]);
dp[x][3] = max(dp[x][3], best[1] + dp[v.f][3]);
dp[x][3] = max(dp[x][3], best[1] + dp[v.f][1]);
for(int i = 0; i< 4; i++)best[i]=max(best[i], dp[v.f][i]);
}
dp[x][0] = max(best[1]+w, 0LL)+sum;
dp[x][1] = sum + w;
dp[x][2] = max({dp[x][2], best[2], best[3]+w})+sum;
dp[x][3] = max(dp[x][3], best[2])+sum+w;
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n;
for(int i = 1; i < n; i++){
int a, b, w;
cin >> a >> b >> w;
tree[a].push_back({b, w});
tree[b].push_back({a, w});
}
dfs(1, 0, 0);
cout << max(dp[1][1] , dp[1][3]);
}
