#include<bits/stdc++.h>
#define reg register
// #define int long long
const int N=1e5+10,mod=1e9+7;
int n,ans,sz[N],son[N],fw[N],S;
std::vector<std::pair<int,int>> G[N];
struct Node{std::pair<int,int> L,R; int ans,len;}t[N<<2];
inline Node operator+(reg Node A,reg Node B){
	reg Node res; res={A.L,B.R,(A.ans+B.ans)%mod,res.len=A.len+B.len};
	auto [x1,y1]=A.R; auto [x2,y2]=B.L;
	if (x1==x2) res.ans=(res.ans+(1ll*(y1+y2)*(y1+y2+1)>>1)-(1ll*y1*(y1+1)>>1)-(1ll*y2*(y2+1)>>1))%mod;
	if (A.L.second==A.len&&A.L.first==B.L.first) res.L.second=A.len+B.L.second;
	if (B.R.second==B.len&&B.R.first==A.R.first) res.R.second=B.len+A.R.second;
	return res;
}
void modify(reg int o,reg int l,reg int r,reg int x,reg int k){
	if (l==r) return t[o]={{k,1},{k,1},1,1},void(); reg int mid=l+r>>1;
	x<=mid?modify(o<<1,l,mid,x,k):modify(o<<1|1,mid+1,r,x,k); t[o]=t[o<<1]+t[o<<1|1];
}
void build(reg int o,reg int l,reg int r){
	if (l==r) return t[o]={{0,1},{0,1},1,1},void(); reg int mid=l+r>>1;
	build(o<<1,l,mid),build(o<<1|1,mid+1,r); t[o]=t[o<<1]+t[o<<1|1];
}
int tp,stk[N];
void Dfs(reg int u,reg int fa=0){
	reg int his=tp;
	for (auto [v,w]:G[u]) if (v!=fa&&v!=son[u]){
		reg int lst=tp;
		Dfs(v,u),ans=(ans+1ll*fw[v]*(S+mod-t[1].ans))%mod;
		for (reg int i=lst+1;i<=tp;i++) modify(1,1,n,stk[i],0);
	}
	if (son[u]){
		Dfs(son[u],u),ans=(ans+1ll*fw[son[u]]*(S+mod-t[1].ans))%mod;
	}
	for (reg int i=his+1;i<=tp;i++) modify(1,1,n,stk[i],1);
	stk[++tp]=u,modify(1,1,n,u,1);
}
void dfs(reg int u,reg int fa=0){
	sz[u]=1;
	for (auto [v,w]:G[u]) if (v^fa) fw[v]=w,dfs(v,u),sz[u]+=sz[v],sz[son[u]]<sz[v]?son[u]=v:0;
}
inline void add(reg int u,reg int v,reg int w){G[u].push_back({v,w}),G[v].push_back({u,w});}
int maintenance_costs_sum(std::vector<int> U, std::vector<int> V, std::vector<int> W) {
	n=U.size()+1,S=1ll*n*(n+1)/2%mod; 
	for (reg int i=0;i<n-1;i++) add(U[i]+1,V[i]+1,W[i]);
	build(1,1,n),dfs(1);
	// for (reg int i=1;i<=n;i++) std::cerr<<i<<" "<<son[i]<<"\n";
	Dfs(1);
	return ans;
}