#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
using ld = long double;
template <typename T>
using V = vector<T>;
template <typename T>
using VV = vector<vector<T>>;
const ll mod = 1000000007;
const ll INF = 1000000099;
const ll LINF = (ll)(1e18 + 99);
const vector<ll> dx = {-1, 1, 0, 0}, dy = {0, 0, -1, 1};
template <typename T, typename U>
inline bool chmin(T& t, const U& u) {
  if (t > u) {
    t = u;
    return 1;
  }
  return 0;
}
template <typename T, typename U>
inline bool chmax(T& t, const U& u) {
  if (t < u) {
    t = u;
    return 1;
  }
  return 0;
}
template <typename T>
inline T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <typename T, typename Y>
inline T mpow(T a, Y n) {
  T res = 1;
  for (; n; n >>= 1) {
    if (n & 1) res = res * a;
    a = a * a;
  }
  return res;
}
const ll MAX = 200010;
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;
}
signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);
  COMinit();
  ll n, ans = 0;
  cin >> n;
  V<ll> v(n), sum(n + 1, 0);
  for (ll i = 0; i < (ll)(n); ++i) cin >> v[i];
  for (ll i = 1; i < (ll)(n + 1); ++i) {
    sum[i] = sum[i - 1] + v[i - 1];
  }
  for (ll i = 0; i < (ll)(n - 1); ++i) {
    for (ll j = i + 1; j < (ll)(n); ++j) {
      ll res = 0;
      if (j == n - 1) {
        res += (v[j] - v[i]) * finv[j - i];
        res %= mod;
        res *= fac[j - i - 1];
        res %= mod;
        ans += res;
      } else {
        res += (v[j] - v[i]) * finv[j - i + 1];
        res %= mod;
        res *= fac[j - i - 1];
        res %= mod;
        ans += res;
      }
      ans %= mod;
    }
  }
  ans *= fac[n - 1];
  ans %= mod;
  cout << ans << '\n';
}
