#include <bits/stdc++.h>
#define ll long long
using namespace std;
struct node{
ll u,v,w;
}e[100005];
ll fa[100005],cnt[100005],cntx,cnty,w,ans;
ll cmp(node x,node y){
if(x.w<y.w) return 1;
return 0;
};
ll getfather(ll q){
if(fa[q]!=q){
fa[q]=getfather(fa[q]);
}
return fa[q];
}
int main(){
ll n;
cin>>n;
for(ll i=1;i<n;i++){
ll x,y,z;
cin>>x>>y>>z;
e[i].u=x;e[i].v=y;e[i].w=z;
ans+=e[i].w;
}
sort(e+1,e+n,cmp);
for(ll i=1;i<=n;i++){
fa[i]=i;
cnt[i]=1;
}
ll fu,fv,s=0;
for(ll i=1;i<=n;i++){
fu=getfather(e[i].u);
fv=getfather(e[i].v);
if(fu!=fv){
s++;
ans+=(cnt[fu]*cnt[fv]-1)*(e[i].w+1);
cnt[fv]+=cnt[fu];
fa[fu]=fv;
}
if(s==n-1)break;
}
cout<<ans<<endl;
return 0;
}