#include <iostream>

using namespace std;

long long u[100010], v[100010], w[100010];

int main()
{
	int n, a[100010];
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}

	u[0] = 1;
	int mod = 1000000007;
	for (int i = 1; i <= n; i++) {
		u[i] = u[i - 1] * i;
		u[i] %= mod;
	}

	v[0] = 1;
	for (int i = 1; i < n - 1; i++) {
		v[i] = v[i - 1] * (i + 1) + u[i];
		v[i] %= mod;
	}

	w[n - 1] = 1;
	for (int i = n - 2; i >= 0; i--) {
		w[i] = w[i + 1] * (i + 1);
		w[i] %= mod;
	}

	long long ans = 0;
	long long t;
	for (int i = 0; i < n - 1; i++) {
		t = (a[i + 1] - a[i]) * w[i + 1];
		t %= mod;
		t *= v[i];
		t %= mod;
		ans += t;
		ans %= mod;
	} 
	cout << ans << endl;

	return 0;
}