#include<deque>
#include<queue>
#include<vector>
#include<algorithm>
#include<iostream>
#include<set>
#include<cmath>
#include<tuple>
#include<string>
#include<chrono>
#include<functional>
#include<iterator>
#include<random>
#include<unordered_set>
#include<array>
#include<map>
#include<iomanip>
#include <assert.h>
using namespace std;
typedef long long int llint;
typedef long double lldo;
#define mp make_pair
#define mt make_tuple
#define pub push_back
#define puf push_front
#define pob pop_back
#define pof pop_front
#define fir first
#define sec second
#define res resize
#define ins insert
#define era erase
//cout<<setprecision(20)
//cin.tie(0);
//ios::sync_with_stdio(false);
const llint mod=1000000007;
const llint big=2.19e15+1;
const long double pai=3.141592653589793238462643383279502884197;
const long double eps=1e-15;
template <class T,class U>void mineq(T& a,U b){if(a>b){a=b;}}
template <class T,class U>void maxeq(T& a,U b){if(a<b){a=b;}}
llint gcd(llint a,llint b){if(a%b==0){return b;}else return gcd(b,a%b);}
llint lcm(llint a,llint b){return a/gcd(a,b)*b;}
template<class T> void SO(T& ve){sort(ve.begin(),ve.end());}
template<class T> void REV(T& ve){reverse(ve.begin(),ve.end());}
int LBI(vector<int>&ar,llint in){return lower_bound(ar.begin(),ar.end(),in)-ar.begin();}
int UBI(vector<int>&ar,llint in){return upper_bound(ar.begin(),ar.end(),in)-ar.begin();}
vector<vector<pair<int,llint>>>go;//行先,長さ
pair<llint,llint>solve(int ter,int per){
if(go[ter].size()==1){return mp(0,go[ter][0].sec);}//葉
llint ans=0,sa=-big,sb=-big,zn=0;
for(auto it:go[ter]){
if(it.fir==per){zn=it.sec;continue;}
auto pa=solve(it.fir,ter);
ans+=pa.fir;
if(pa.sec>sb){swap(sb,pa.sec);}
if(sb>sa){swap(sa,sb);}
}
//現在のスコア,上を使うことによるマイナス値
llint hos=max(0LL,sa+max(sb,zn));
return mp(ans+hos,zn+max(0LL,sa+sb)-hos);
}
int main(void){
int n;cin>>n;go.res(n);n--;
while(n--){
int a,b;llint c;
cin>>a>>b>>c;a--;b--;
go[a].pub(mp(b,c));
go[b].pub(mp(a,c));
}
go[0].pub(mp(-1,-big));
cout<<solve(0,-1).fir<<endl;
return 0;
}
