#include <bits/stdc++.h>
using namespace std;
class ModInt {
  static int MOD;
  long long x;

 public:
  static void mod(int m) { MOD = m; }
  ModInt(long long v = 0) : x(v % MOD) {
    if (x < 0) x += MOD;
  }
  ModInt& operator+=(const ModInt& r) {
    x += r.x;
    if (x >= MOD) x -= MOD;
    return *this;
  }
  ModInt& operator-=(const ModInt& r) {
    x -= r.x;
    if (x < 0) x += MOD;
    return *this;
  }
  ModInt& operator*=(const ModInt& r) {
    x = (x * r.x) % MOD;
    return *this;
  }
  ModInt& operator/=(const ModInt& r) {
    *this *= r.inverse();
    return *this;
  }
  ModInt operator-() const { return ModInt(-x); }
  ModInt operator+(const ModInt& r) const { return ModInt(*this) += r; }
  ModInt operator-(const ModInt& r) const { return ModInt(*this) -= r; }
  ModInt operator*(const ModInt& r) const { return ModInt(*this) *= r; }
  ModInt operator/(const ModInt& r) const { return ModInt(*this) /= r; }
  bool operator==(const ModInt& r) const { return x == r.x; }
  bool operator!=(const ModInt& r) const { return x != r.x; }
  ModInt inverse() const {
    long long a = x, b = MOD, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }
  ModInt pow(long long n) const {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1) ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }
  friend ostream& operator<<(ostream& os, const ModInt& x) { return os << x.x; }
  friend istream& operator>>(istream& is, ModInt& x) { return is >> x.x; }
  int getMod() { return MOD; }
  long long val() { return x; }
};
int ModInt::MOD = 1000000007;
template <typename T>
class Combination {
  vector<T> fact, ifact;

 public:
  Combination(int nMax) : fact(nMax + 1), ifact(nMax + 1) {
    fact[0] = 1;
    for (int i = 0; i < nMax; ++i) fact[i + 1] = fact[i] * (i + 1);
    for (int i = 0; i < nMax + 1; ++i) ifact[i] = fact[i].inverse();
  }
  T factorial(int n) const { return fact[n]; }
  T inverseFactorial(int n) const { return ifact[n]; }
  T P(int n, int k) const {
    if (n < 0 || k < 0 || n < k) return 0;
    return factorial(n) * inverseFactorial(n - k);
  }
  T C(int n, int k) const {
    if (n < 0 || k < 0 || n < k) return 0;
    return factorial(n) * inverseFactorial(n - k) * inverseFactorial(k);
  }
  T H(int n, int k) const {
    if (n < 0 || k < 0) return 0;
    return k == 0 ? 1 : C(n + k - 1, k);
  }
};
int N;
vector<int> x;
int main() {
  cin >> N;
  x.resize(N);
  for (int i = 0; i < (int)N; ++i) cin >> x[i];
  Combination<ModInt> comb(N + 1);
  ModInt ans = 0;
  for (int k = 0; k < (int)N - 1; ++k) {
    for (int j = 1; k + j < N - 1; ++j) {
      ans += comb.C(N - 1, j + 1) * comb.factorial(j - 1) *
             comb.factorial(N - 2 - j) * (x[k + j] - x[k]);
    }
    for (int j = 0; j <= k; ++j) {
      ans += comb.P(k, j) * comb.factorial(N - 2 - j) * (x[N - 1] - x[k]);
    }
  }
  cout << ans << endl;
  return 0;
}
