#include <bits/stdc++.h>
using namespace std;
using lint = int64_t;
using uint = uint32_t;
using ulint = uint64_t;
template <class T>
using vector2d = vector<vector<T>>;
template <class T>
bool UpdateMax(T& a, const T& b) {
  if (a < b) {
    a = b;
    return true;
  } else {
    return false;
  }
}
template <class T>
bool UpdateMin(T& a, const T& b) {
  if (a > b) {
    a = b;
    return true;
  } else {
    return false;
  }
}
template <class T>
void OutVec(const vector<T>& vec) {
  for (int i = 0; i < vec.size() - 1; ++i) {
    cout << vec[i] << " ";
  }
  cout << vec.back() << endl;
}
template <class T>
void OutVec2d(const vector2d<T>& vec) {
  for (auto v : vec) {
    OutVec(v);
  }
}
int64_t EuclidMod(int64_t v, int64_t m) {
  if (0 <= v && v < m) {
    return v;
  } else if (-m <= v && v < 0) {
    return v + m;
  } else {
    int64_t result = v % m;
    if (result < 0) {
      result += m;
    }
    return result;
  }
}
int64_t ModInv(int64_t a, int64_t m) {
  int64_t b = m, u = 1, v = 0;
  while (b) {
    int64_t t = a / b;
    a -= t * b;
    std::swap(a, b);
    u -= t * v;
    std::swap(u, v);
  }
  EuclidMod(u, m);
  return u;
}
int64_t RepeatedPowMod(int64_t base, int64_t exponent, int64_t mod) {
  if (exponent == 0)
    return 1;
  else if (exponent % 2 == 0) {
    int64_t root = RepeatedPowMod(base, exponent / 2, mod);
    return (root * root) % mod;
  } else {
    return (base * RepeatedPowMod(base, exponent - 1, mod)) % mod;
  }
}
template <int64_t mod>
class ModInt {
  int64_t value_;

 public:
  explicit ModInt(const int64_t x = 0) : value_(x % mod){};
  ModInt& operator=(const ModInt& another) {
    value_ = another.value_;
    return *this;
  }
  ModInt& operator^=(const ModInt& another) {
    value_ = RepeatedPowMod(value_, another.value_, mod);
    return *this;
  }
  ModInt& operator+=(const ModInt& another) {
    value_ += another.value_;
    value_ = EuclidMod(value_, mod);
    return *this;
  }
  ModInt& operator-=(const ModInt& another) {
    value_ -= another.value_;
    value_ = EuclidMod(value_, mod);
    return *this;
  }
  ModInt& operator*=(const ModInt& another) {
    value_ *= another.value_;
    value_ = EuclidMod(value_, mod);
    return *this;
  }
  ModInt& operator/=(const ModInt& another) {
    value_ = value_ * ModInv(another.value_, mod);
    value_ = EuclidMod(value_, mod);
    return *this;
  }
  ModInt& operator++() {
    value_ += 1;
    value_ = EuclidMod(value_, mod);
    return *this;
  }
  ModInt operator++(int) {
    ModInt tmp = *this;
    this->value_ += 1;
    this->value_ = EuclidMod(this->value_, mod);
    return tmp;
  }
  ModInt& operator--() {
    value_ -= 1;
    value_ = EuclidMod(value_, mod);
    return *this;
  }
  ModInt operator--(int) {
    ModInt tmp = *this;
    this->value_ -= 1;
    this->value_ = EuclidMod(this->value_, mod);
    return tmp;
  }
  int64_t GetValue() const { return value_; }
};
template <int64_t mod>
ModInt<mod> operator+(const ModInt<mod>& left, const ModInt<mod>& right) {
  return ModInt<mod>(left) += right;
}
template <int64_t mod>
ModInt<mod> operator-(const ModInt<mod>& left, const ModInt<mod>& right) {
  return ModInt<mod>(left) -= right;
}
template <int64_t mod>
ModInt<mod> operator/(const ModInt<mod>& left, const ModInt<mod>& right) {
  return ModInt<mod>(left) /= right;
}
template <int64_t mod>
ModInt<mod> operator*(const ModInt<mod>& left, const ModInt<mod>& right) {
  return ModInt<mod>(left) *= right;
}
template <int64_t mod>
ModInt<mod> operator^(const ModInt<mod>& left, const ModInt<mod>& right) {
  return ModInt<mod>(left) ^= right;
}
template <int64_t mod>
std::ostream& operator<<(std::ostream& stream, const ModInt<mod>& mod_int) {
  stream << mod_int.GetValue();
  return stream;
}
int main() {
  cout << std::fixed << std::setprecision(16);
  cin.tie(nullptr);
  std::ios::sync_with_stdio(false);
  lint n;
  const int64_t MOD = 1000000007;
  cin >> n;
  vector<lint> x(n);
  for (lint i = 0; i < n; ++i) {
    cin >> x[i];
  }
  vector<ModInt<MOD>> diff(n - 1);
  for (lint i = 0; i < n - 1; i++) {
    diff[i] = ModInt<MOD>(x[i + 1]) - ModInt<MOD>(x[i]);
  }
  vector<ModInt<MOD>> cum(n - 1);
  cum[0] = diff[0];
  ModInt<MOD> cum_sum;
  cum_sum += cum[0];
  for (int i = 1; i < n - 1; ++i) {
    cum[i] = cum[i - 1] + diff[i];
    cum_sum += cum[i];
  }
  ModInt<MOD> result(0);
  ModInt<MOD> multiply(1);
  for (lint i = 1; i < n; i++) {
    multiply *= ModInt<MOD>(i);
  }
  for (lint i = 0; i < n - 1; i++) {
    ModInt<MOD> bunsi(cum_sum);
    ModInt<MOD> tmp_res = bunsi * multiply / ModInt<MOD>(n - 1 - i);
    result += tmp_res;
    cum_sum -= diff[i] * ModInt<MOD>(n - 1 - i);
  }
  cout << result.GetValue() << endl;
  return 0;
}
