#include <bits/stdc++.h>
#define int long long
const int INF = 1e9;
int n;
std::vector<std::pair<int,int>> adj[100000];
int dp[100000][2];
int dfs(int curr,int par){
int mx1=-1,mx2=-1;
int bsum = 0;
if((adj[curr].size()-(int)(curr!=par))>=2){
for(auto [to,w]:adj[curr]){
if(to==par)continue;
dfs(to,curr);
int blue = dp[to][0]+w;
int pick = dp[to][1]+w;
if(blue>0){
bsum+=blue;
pick=(dp[to][1]-dp[to][0]);
}
//std::cout << pick << '|';
if(mx1==-1)mx1=pick;
else if(pick>mx1)mx2=mx1,mx1=pick;
else if(mx2==-1)mx2=pick;
else if(pick>mx2)mx2=pick;
}
if(mx1!=-1&&mx2!=-1)
dp[curr][1]=bsum+mx1+mx2;
else
dp[curr][1]=bsum;
if(mx1!=-1)
dp[curr][0]=bsum+mx1;
else
dp[curr][0]=-INF;
}
if((adj[curr].size()-(int)(curr!=par))==1){
for(auto [to,w]:adj[curr]){
if(to==par)continue;
dp[curr][0]=dp[to][1]+w;
dp[curr][1]=dp[to][0]+w;
}
}
if((adj[curr].size()-(int)(curr!=par))==0){
dp[curr][0]=-INF;
dp[curr][1]=0;
}
//std::cout << curr << ' ' << adj[curr].size()-(int)(curr!=par) << ' ' << mx1 << ' ' << mx2 << ' ' << dp[curr][0] << ' ' << dp[curr][1] << '\n';
return 0;
}
signed main(){
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
std::cin >> n;
for(int i=0;i<n-1;i++){
int x,y,c;
std::cin >> x >> y >> c;
adj[x].push_back({y,c});
adj[y].push_back({x,c});
}
dfs(1,1);
std::cout << dp[1][1];
}
