N=int(input())
M=10**9+7
ans=0
G=[[(0,0)]*0 for i in range(N)]
order=[0]
sub_size=[0]*N
pare=[(-1,0)]*N
lower_sum=[0]*N
upper_sum=[0]*N
for i in range(N-1):
	a,b,c=map(int,input().split())
	a-=1
	b-=1
	G[a].append((b,c))
	G[b].append((a,c))
for i in range(N):
	a=order[i]
	for x in G[a]:
		if pare[a][0]!=x[0]:
			order.append(x[0])
			pare[x[0]]=(a,x[1])
for i in range(N):
	a=order[N-1-i]
	L=pare[a][1]
	for x in G[a]:
		if x[0]!=pare[a][0]:
			sub_size[a]+=sub_size[x[0]]
			lower_sum[a]+=lower_sum[x[0]]
	lower_sum[a]%=M
	sub_size[a]+=1
	ans+=(((sub_size[a]*(N-sub_size[a]))%M)*pow(L,2,M))%M
	ans+=(L*lower_sum[a]*(N-sub_size[a]))%M
	ans%=M
	lower_sum[a]+=L*sub_size[a]
for i in range(N):
	a=order[i]
	L=pare[a][1]
	lower_sum[a]-=(L*sub_size[a])%M
	for x in G[a]:
		if pare[a][0]==x[0]:
			continue
		tmp=(upper_sum[a]+lower_sum[a]-lower_sum[x[0]])%M
		ans+=(x[1]*tmp*sub_size[x[0]])%M
		upper_sum[x[0]]=(tmp+x[1]*(N-sub_size[x[0]]))%M
		ans%=M
print(ans)