#include<bits/stdc++.h>
using namespace std;
int n;
int read(){
	int x=0;
	char c=getchar();
	while(c<'0' || c>'9')c=getchar();
	while(c>='0' && c<='9'){
		x=x*10+c-48;
		c=getchar();
	}
	return x;
}
vector<pair<int,int> >T[500005];
int sz[500005],id[500005];
vector<int>c[500005];
int b[500005],b1[500005];
void dfs1(int x,int fa){
	sz[x]=1;
	for(int i=0;i<T[x].size();i++){
		pair<int,int>e=T[x][i];
		if(e.first==fa)continue;
		dfs1(e.first,x);
		sz[x]+=sz[e.first];
	}
	b[x]=sz[x];
}
void dfs2(int x,int fa,int fw){
	int tmp=id[fw];
	id[fw]=x;
	for(int i=0;i<T[x].size();i++){
		pair<int,int>e=T[x][i];
		if(e.first==fa)continue;
		dfs2(e.first,x,e.second);
	}
	id[fw]=tmp;
//	printf("del %d %d %d %d\n",x,fw,tmp,sz[x]);
	if(tmp==1)b1[fw]-=sz[x];
	else b[tmp]-=sz[x];
	c[fw].push_back(b[x]);
	if(x==1)for(int i=1;i<=n;i++)c[i].push_back(b1[i]);
}
int main(){
	n=read();
	for(int i=1;i<n;i++){
		int u,v,w;
		u=read(),v=read(),w=read();
		T[u].push_back(make_pair(v,w));
		T[v].push_back(make_pair(u,w));
	}
	for(int i=1;i<=n;i++)id[i]=1;
	dfs1(1,0);
	for(int i=1;i<=n;i++)b1[i]=n;
	dfs2(1,0,0);
//	for(int i=1;i<=n;i++)printf("%d ",sz[i]);printf("\n");
//	for(int i=1;i<=n;i++)printf("%d ",b1[i]);printf("\n");
//	for(int i=1;i<=n;i++)printf("%d ",b[i]);printf("\n");
	long long ans=0;
	for(int i=1;i<=n;i++){
		long long sum=1LL*n*n;
//		for(int j=0;j<c[i].size();j++)printf("%d ",c[i][j]);printf("\n");
		for(int j=0;j<c[i].size();j++)sum-=1LL*c[i][j]*c[i][j];
		ans+=sum;
	}
	printf("%lld",ans);
	return 0;
	//quod erat demonstrandum
}