#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
const long long MAX = 200000;
template <typename T>
T gcd(T a, T b) {
  return b != 0 ? gcd(b, a % b) : a;
}
template <typename T>
T lcm(T a, T b) {
  return a * b / gcd(a, b);
}
long long fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}
long long COM(int n, int k) {
  if (n < k) return 0;
  if (n < 0 || k < 0) return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
int main() {
  COMinit();
  long long N;
  cin >> N;
  long long x[N];
  for (int i = 0; i < N; i++) {
    cin >> x[i];
  }
  long long ans = 0;
  long long sugoi = fac[N - 1];
  long long tentou = sugoi / 2;
  long long ll = 0;
  tentou++;
  for (int i = 0; i < N - 1; i++) {
    ans += (x[i + 1] - x[i]) * (sugoi + ll) % MOD;
    ans %= MOD;
    ll += (tentou - 1);
    tentou--;
  }
  cout << ans << endl;
}
