#include<bits/stdc++.h>
//ios::sync_with_stdio(false);
//cin.tie(0);
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<pii,int> ppii;
typedef pair<int,pii> pipi;
typedef pair<ll,ll> pll;
typedef pair<pll,ll> ppll;
typedef pair<ll,pll> plpl;
typedef tuple<ll,ll,ll> tl;
ll mod=1000000007;
ll mod2=998244353;
ll inf=1000000000000000000;
double pi=2*acos(0);
#define rep(i,m,n) for(ll i=m;i<n;i++)
#define rrep(i,n,m) for(ll i=n;i>=m;i--)
int dh[4]={1,-1,0,0};
int dw[4]={0,0,1,-1};
int ddh[8]={-1,-1,-1,0,0,1,1,1};
int ddw[8]={-1,0,1,-1,1,-1,0,1};
ll lmax(ll a,ll b){
    if(a<b)return b;
    else return a;
}
ll lmin(ll a,ll b){
    if(a<b)return a;
    else return b;
}
ll gcd(ll a,ll b){
    if(a<b)swap(a,b);
    if(a%b==0)return b;
    return gcd(b,a%b);
}
ll Pow(ll n,ll k){
    ll ret=1;
    ll now=n;
    while(k>0){
        if(k&1)ret*=now;
        now*=now;
        k/=2;
    }
    return ret;
}
ll gya[200010];
ll kai[200010];
ll m;
ll beki(ll n,ll k){
  ll ret=1;
  ll now=n;
  while(k>0){
    if(k%2==1){
      ret*=now;
      ret%=m;
    }
    now*=now;
    now%=m;
    k/=2;
  }
  return ret;
}
ll gyaku(ll n){
  return beki(n,mod-2);
}
void nckinit(ll n){
  kai[0]=1;
  kai[1]=1;
  for(int i=2;i<=n;i++){
    kai[i]=kai[i-1]*i;
    kai[i]%=mod;
  }
  gya[n]=gyaku(kai[n]);
  for(int i=n-1;i>=1;i--){
    gya[i]=gya[i+1]*(i+1);
    gya[i]%=mod;
  }
  gya[0]=1;
}    
ll nck(ll n,ll k){
  if(k<0)return 0;
  if(k==0||n==k)return 1;
  ll ret=kai[n];
  ret*=gya[n-k];
  ret%=mod;
  ret*=gya[k];
  ret%=mod;
  return ret;
}
ll npk(ll n,ll k){
  if(k<0)return 0;
  if(k==0)return 1;
  ll ret=kai[n];
  ret*=gya[n-k];
  ret%=mod;
  return ret;
}
ll dp[200010];
vector<pll> v[200010];
void dfs(ll now,ll par){
  
    ll ret=0;
    rep(i,0,v[now].size()){
      ll ne=v[now][i].first;
      if(ne==par)continue;
      dfs(ne,now);
      ret+=dp[ne];
      
    }
    dp[now]=ret+1;
  
}
int main(){
  int n;cin>>n;
  rep(i,0,n-1){
    ll a,b,c;cin>>a>>b>>c;
    v[a].push_back({b,c});
    v[b].push_back({a,c});
  }
  ll d[n+1];
  fill(d,d+n+1,inf);
  d[1]=0;
  queue<ll> q;
  q.push(1);
  while(q.size()>0){
    ll now=q.front();q.pop();
    rep(i,0,v[now].size()){
      pll p=v[now][i];
      ll ne=p.first;ll co=p.second;
      if(d[ne]<inf)continue;
      d[ne]=d[now]+co;
      q.push(ne);
    }
  }
  dfs(1,-1);
  ll sum[n+1];
  fill(sum,sum+n+1,0);
  rep(i,1,n+1)sum[1]+=d[i];
  q.push(1);
  while(q.size()>0){
    ll now=q.front();q.pop();
    rep(i,0,v[now].size()){
      ll ne=v[now][i].first;
      if(sum[ne]>0)continue;
      sum[ne]=sum[now]+(n-dp[ne]*2)*v[now][i].second;
      q.push(ne);
    }
  }
  ll ans=0;
  rep(i,1,n+1)ans+=sum[i];
  cout<<ans<<endl;
  //rep(i,1,n+1)cout<<sum[i]<<" ";
}