solve.py

import sys

mod = 10 ** 9 + 7

def read_and_split():
	ret = []
	for i in input().split():
		ret.append(int(i))
	return ret

n = read_and_split()[0]

graf = []

for i in range(n):
	graf.append([])

for i in range(1, n):
	a, b = read_and_split()
	a -= 1
	b -= 1
	graf[a].append(b)
	graf[b].append(a)

def choose(d, at_least):
	global mod
	ret = 0
	x = 1
	if at_least == 0:
		ret = 1
	for i in range(1, d + 1):
		x = (x * (d + 1 - i)) % mod
		if i >= at_least:
			ret += x
	return ret % mod

wyn = n - 1
for i in range(n):
	wyn += choose(len(graf[i]), 2)
wyn %= mod

def dfs(v, oj):
	global graf, wyn, mod
	d = len(graf[v])
	ret = choose(d - 1, 1)
	mul = choose(d - 2, 0)
	for i in graf[v]:
		if i == oj:
			continue
		take = dfs(i, v)
		wyn = (wyn + 2 * ret * take) % mod
		ret = (ret + mul * take) % mod
	return ret

sys.setrecursionlimit(10 ** 6)
dfs(0, -1)

print(wyn)