#include<bits/stdc++.h>
using namespace std;
#define inf INT_MAX
#define INF LLONG_MAX
#define ll long long
#define ull unsigned long long
#define M (int)(1e9+7)
#define P pair<int,int>
#define PLL pair<ll,ll>
#define FOR(i,m,n) for(int i=(int)m;i<(int)n;i++)
#define RFOR(i,m,n) for(int i=(int)m;i>=(int)n;i--)
#define rep(i,n) FOR(i,0,n)
#define rrep(i,n) RFOR(i,n,0)
#define all(a) a.begin(),a.end()
#define IN(a,n) rep(i,n){ cin>>a[i]; }
const int vx[4] = {0,1,0,-1};
const int vy[4] = {1,0,-1,0};
#define PI 3.14159265
#define F first
#define S second
#define PB push_back
#define EB emplace_back
#define int ll
#define vi vector<int>
#define IP pair<int,P>
#define PP pair<P,P>
#define Yes(f){cout<<(f?"Yes":"No")<<endl;}
#define YES(f){cout<<(f?"YES":"NO")<<endl;}



template< typename T >
struct edge {
  int src, to;
  T cost;

  edge(int to, T cost) : src(-1), to(to), cost(cost) {}

  edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

  edge &operator=(const int &x) {
    to = x;
    return *this;
  }

  operator int() const { return to; }
};

template< typename T >
using Edges = vector< edge< T > >;
template< typename T >
using WG = vector< Edges< T > >;
using UG = vector< vector< int > >;
template< typename T >
using Matrix = vector< vector< T > >;


signed main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout<<fixed<<setprecision(20);

  int n;
  cin>>n;
  WG<int> es(n);
  rep(i,n-1){
    int a,b,c;
    cin>>a>>b>>c;
    a--;b--;
    es[a].PB(edge<int>(b,c));
    es[b].PB(edge<int>(a,c));
  }

  queue<P> q;
  rep(i,n){
    if(es[i].size()==1){
      q.push(P(i,1));
    }
  }
  bool b[210000]={};
  int ans=0;

  while(q.size()){
    P p=q.front(); q.pop();
    b[p.F]=true;
    //cout<<p.F<<' '<<p.S<<endl;
    for(auto e:es[p.F]){
      if(b[e.to]) continue;
      ans+=2*e.cost*(n-p.S);
      q.push(P(e.to,p.S+1));

    }
  }

  cout<<ans<<endl;

}