from collections import defaultdict
MOD = 10**9 + 7
inpl = lambda: list(map(int,input().split()))
N = int(input())
children = [[] for _ in range(N)]
parent = [None] * N
for _ in range(N-1):
    A, B = inpl()
    A, B = A-1, B-1
    children[A].append(B)
    parent[B] = A

layer = defaultdict(int)
forward, back = 0, 1
root = parent.index(None)
pool = [(root,0)]
while pool:
    node, d = pool.pop()
    layer[d] += 1
    for c in children[node]:
        pool.append((c, d+1))

ans = 0
for d, n in layer.items():
    ans += n*d*(d+1)//2
    ans %= MOD
print(ans)