from math import factorial
from itertools import accumulate

N=int(input())
x=list(map(int, input().split()))

C=0
t=[math.factorial(N-i) for i in range(2,N)]

t=list(itertools.accumulate(t))
t.append(math.factorial(N-1))
t.reverse()
T=list(itertools.accumulate(t))

C=[(x[j]-x[j-1])*T[j-1] for j in range(1,N) ]

print(sum(C)%((10 ** 9)+7))