#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pli = pair<ll, int>;
const int INF = 0x3f3f3f3f, N = 1e5 + 5;
const ll LINF = 1e18 + 5;
constexpr int mod = 1e9 + 7, two = (mod + 1) / 2;
int n, x[N], d[N];
ll sum[N];
ll fac[N], inv[N];
ll powmod(ll a, ll b) {
  ll ans = 1;
  while (b) {
    if (b & 1) ans = ans * a % mod;
    a = a * a % mod;
    b >>= 1;
  }
  return ans;
}
void init() {
  fac[0] = 1;
  for (int i = 1; i <= n; i++) fac[i] = fac[i - 1] * i % mod;
  inv[n] = powmod(fac[n], mod - 2);
  for (int i = n - 1; i >= 0; i--) inv[i] = inv[i + 1] * (i + 1) % mod;
}
ll comp(ll a, ll b) {
  if (a < b || b < 0) return 0;
  return fac[a] * inv[b] % mod * inv[a - b] % mod;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> x[i];
  for (int i = 1; i < n; i++) d[i] = x[i + 1] - x[i];
  for (int i = 1; i < n; i++) sum[i] = (sum[i - 1] + d[i]) % mod;
  init();
  ll res = 0;
  for (int i = 1; i < n - 1; i++) {
    for (int j = 1; j + i < n; j++) {
      ll cur = d[j + i] * comp(n - 1, i + 1) % mod * fac[n - i - 2] % mod *
               fac[i] % mod;
      res = (res + cur) % mod;
    }
  }
  res = (res + fac[n - 1] * sum[n - 1] % mod) % mod;
  res = (res + mod) % mod;
  cout << res;
  return 0;
}
