#include <bits/stdc++.h>
using namespace std;
const long long INFL = 1LL << 60;
const long long INF = 1 << 30;
long long MOD = 1000000007;
vector<long long> dy = {0, 1, 0, -1, 1, 1, -1, -1, 0};
vector<long long> dx = {1, 0, -1, 0, 1, -1, 1, -1, 0};
void pres(double A, long long x = 10) {
  cout << fixed << setprecision(x) << A << endl;
}
void BinarySay(long long x, long long y = 60) {
  for (long long i = 0; i < (y); i++) cout << (x >> (y - 1 - i) & 1);
  cout << endl;
}
long long cnt_bit(long long x) { return __builtin_popcountll(x); }
long long pow_long(long long x, long long k) {
  long long res = 1;
  while (k > 0) {
    if (k % 2) res *= x;
    x *= x;
    k /= 2;
  }
  return res;
}
long long pow_mod(long long x, long long k) {
  long long res = 1;
  while (k > 0) {
    if (k % 2) {
      res *= x;
      res %= MOD;
    }
    x *= x;
    x %= MOD;
    k /= 2;
  }
  return res;
}
long long inverse(long long x) { return pow_mod(x, MOD - 2); };
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long x, long long y) {
  long long res = x / gcd(x, y);
  res *= y;
  return res;
};
const int MAXcomb = 200010;
long long fac[MAXcomb], finv[MAXcomb], inv[MAXcomb];
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAXcomb; 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 comb(int n, int k) {
  if (n < k) return 0;
  if (n < 0 || k < 0) return 0;
  return fac[n] * finv[k] % MOD * finv[n - k] % MOD;
}
long long memo_kai[100010];
long long kai(long long N) {
  if (memo_kai[N] != 0) return memo_kai[N];
  if (N <= 1) return 1;
  return N * kai(N - 1) % MOD;
}
void solve() {
  long long N;
  cin >> N;
  vector<long long> A(N);
  for (long long i = 0; i < (N); i++) cin >> A[i];
  vector<long long> X(N + 10);
  X[0] = 0;
  for (long long i = 0; i < (N); i++) {
    X[i + 1] = (i + 1) * X[i] % MOD + kai(i);
    X[i + 1] %= MOD;
  }
  long long ans = 0;
  for (long long i = 0; i < (N - 1); i++) {
    long long add = A[i + 1] - A[i];
    add = add * X[i + 1] % MOD * kai(N - 1) % MOD * inverse(kai(i + 1)) % MOD;
    ans += add;
    ans %= MOD;
  }
  cout << ans << endl;
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  solve();
}
