There are N slimes standing on a number line. The i-th slime from the left is at position x_i.

It is guaruanteed that 1 \leq x_1 < x_2 < \ldots < x_N \leq 10^{9}.

Niwango will perform N-1 operations. The i-th operation consists of the following procedures:

* Choose an integer k between 1 and N-i (inclusive) with equal probability.
* Move the k-th slime from the left, to the position of the neighboring slime to the right.
* Fuse the two slimes at the same position into one slime.



Find the total distance traveled by the slimes multiplied by (N-1)! (we can show that this value is an integer), modulo (10^{9}+7). If a slime is born by a fuse and that slime moves, we count it as just one slime.

Constraints

* 2 \leq N \leq 10^{5}
* 1 \leq x_1 < x_2 < \ldots < x_N \leq 10^{9}
* x_i is an integer.

Input

Input is given from Standard Input in the following format:


N
x_1 x_2 \ldots x_N


Output

Print the answer.

Examples

Input

3
1 2 3


Output

5


Input

12
161735902 211047202 430302156 450968417 628894325 707723857 731963982 822804784 880895728 923078537 971407775 982631932


Output

750927044
n = int(input())
xl = list(map(int,input().split()))

bl = []

for i in range(n-1):
    bl.append(xl[i+1] - xl[i])

import itertools
bl_ac = list(itertools.accumulate(bl))

MOD = 10**9 + 7
N = 10**5

fact = [1]*(N+1)
rfact = [1]*(N+1)
r = 1
for i in range(1, N+1):
  fact[i] = r = r * i % MOD
rfact[N] = r = pow(fact[N], MOD-2, MOD)
for i in range(N, 0, -1):
  rfact[i-1] = r = r * i % MOD

# nPk (mod MOD) を求める
def perm(n, k):
  return fact[n] * rfact[n-k] % MOD

# nCk (mod MOD) を求める
def comb(n, k):
  return fact[n] * rfact[k] * rfact[n-k] % MOD

ans = 0
p = 1
c = 1
for i in range(n-1):
    ans += bl[i] * perm(n-1, n-2-i) * c
    ans %= MOD
    c *= i + 2
    c += p
    c %= MOD
    p *= i + 2
    p %= MOD

print(ans)