class PERM_COMB_MOD():
    def __init__(self, max_n=510000, mod=10**9+7):
        self.fac = [0]*max_n
        self.finv = [0]*max_n
        self.inv = [0]*max_n
        self.fac[0] = self.fac[1] = 1
        self.finv[0] = self.finv[1] = 1
        self.inv[1] = 1
        self.max = max_n
        self.mod = mod
        self._maesyori()

    def _maesyori(self):
        for i in range(2,self.max):
            self.fac[i] = self.fac[i-1] * i % self.mod
            self.inv[i] = self.mod - self.inv[self.mod % i] * (self.mod // i) % self.mod
            self.finv[i] = self.finv[i-1] * self.inv[i] % self.mod

    def perm(self, n, k):
        if n < k : return 0
        if n < 0 or k < 0:return 0
        return self.fac[n] * self.finv[n-k] % self.mod % self.mod

    def comb(self, n, k):
        if n < k : return 0
        if n < 0 or k < 0:return 0
        return self.fac[n] * (self.finv[k] * self.finv[n-k] % self.mod) % self.mod

mod = 10**9+7
P = PERM_COMB_MOD(2*10**5, mod=mod)

n = int(input())
x = list(map(int, input().split()))
base = x[-1]-x[0]
left = []
k = n-1
for i in range(k):
    a = P.perm(k, k-(i+1))*P.fac[i]
    left.append(a)
ans = base*P.fac[k]
for i in range(k):
    for j in range(1, n-1-i):
        ans += left[j]*(x[i+j+1]-x[i+j])
        ans %= mod
print(ans)
