#include <bits/stdc++.h>
using namespace std;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &vec) {
  for (auto &v : vec) is >> v;
  return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &vec) {
  for (int i = 0; i < vec.size(); i++) {
    os << vec[i];
    if (i + 1 != vec.size()) os << " ";
  }
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const set<T> &st) {
  for (auto itr = st.begin(); itr != st.end(); ++itr) {
    os << *itr;
    auto titr = itr;
    if (++titr != st.end()) os << " ";
  }
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_set<T> &st) {
  for (auto itr = st.begin(); itr != st.end(); ++itr) {
    os << *itr;
    auto titr = itr;
    if (++titr != st.end()) os << " ";
  }
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const multiset<T> &st) {
  for (auto itr = st.begin(); itr != st.end(); ++itr) {
    os << *itr;
    auto titr = itr;
    if (++titr != st.end()) os << " ";
  }
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const unordered_multiset<T> &st) {
  for (auto itr = st.begin(); itr != st.end(); ++itr) {
    os << *itr;
    auto titr = itr;
    if (++titr != st.end()) os << " ";
  }
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << p.first << " " << p.second;
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const map<T1, T2> &mp) {
  for (auto itr = mp.begin(); itr != mp.end(); ++itr) {
    os << itr->first << ":" << itr->second;
    auto titr = itr;
    if (++titr != mp.end()) os << " ";
  }
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp) {
  for (auto itr = mp.begin(); itr != mp.end(); ++itr) {
    os << itr->first << ":" << itr->second;
    auto titr = itr;
    if (++titr != mp.end()) os << " ";
  }
  return os;
}
using ll = long long int;
using P = pair<int, int>;
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1000000007;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};
struct fast_io {
  fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(20);
  }
} fast_io_;
template <typename T>
T power(T a, T n, T mod) {
  T res = 1;
  T tmp = n;
  T curr = a;
  while (tmp) {
    if (tmp % 2 == 1) {
      res = (T)(res * curr % mod);
    }
    curr = (T)(curr * curr % mod);
    tmp >>= 1;
  }
  return res;
}
struct Factorial {
  int n = 0;
  static const long long mod_default = 1e9 + 7;
  long long MOD = mod_default;
  vector<long long> fac;
  vector<long long> inv_;
  explicit Factorial() {}
  explicit Factorial(int n, long long mod_ = mod_default) : n(n), MOD(mod_) {
    assert(MOD > 0 && n < MOD);
    fac.resize(n + 1);
    inv_.resize(n + 1);
    calc_factorial();
    calc_inv();
  }
  void calc_factorial() {
    fac[0] = 1;
    for (int i = 1; i <= n; i++) {
      fac[i] = i * fac[i - 1] % MOD;
    }
  }
  void calc_inv() {
    inv_[n] = power<long long>(fac[n], MOD - 2, MOD);
    for (int i = n - 1; i >= 0; i--) {
      inv_[i] = (i + 1) * inv_[i + 1] % MOD;
    }
  }
  long long &operator[](size_t i) {
    if ((int)i > n) {
      cerr << "list index out of range" << endl;
      abort();
    }
    return fac[i];
  }
  long long inv(size_t i) {
    if ((int)i > n) {
      cerr << "list index out of range" << endl;
      abort();
    }
    return inv_[i];
  }
  long long comb(int n, int k) {
    if (n < 0 || k < 0 || n < k) return 0;
    long long res = fac[n];
    res = res * inv_[n - k] % MOD;
    res = res * inv_[k] % MOD;
    return res;
  }
  long long perm(int n, int k) {
    if (n < 0 || k < 0 || n < k) return 0;
    long long res = fac[n];
    res = res * inv_[n - k] % MOD;
    return res;
  }
  long long h(int n, int k) {
    if (n == 0 && k == 0) return 1;
    return comb(n + k - 1, k);
  }
};
template <typename T>
T extgcd(T a, T b, T &x, T &y) {
  T d = a;
  if (b != 0) {
    d = extgcd(b, a % b, y, x);
    y -= (a / b) * x;
  } else {
    x = 1, y = 0;
  }
  return d;
}
template <typename T>
T modinv(T a, T m) {
  long long x = 0, y = 0;
  extgcd<long long>(a, m, x, y);
  x %= m;
  if (x < 0) x += m;
  return x;
}
int main(int argc, char const *argv[]) {
  int n;
  cin >> n;
  Factorial fac(200010);
  vector<ll> x(n);
  cin >> x;
  ll res = 0;
  vector<ll> acc(n, 0);
  for (int i = (0); i < (n); ++i) {
    acc[i] = x[i];
    if (i > 0) acc[i] += acc[i - 1];
  }
  for (int i = (0); i < (n - 1); ++i) {
    res = (res + modinv<ll>(n - 1 - i, mod) * (x[n - 1] - x[i])) % mod;
  }
  for (int k = 1; k < n - 1; k++) {
    if (n - 2 - k < 0) continue;
    ll as = modinv<ll>(k, mod) * modinv<ll>(k + 1, mod) % mod;
    ll tmp = acc[n - 2] - acc[k - 1];
    tmp -= acc[n - 2 - k];
    res = (res + as * tmp % mod) % mod;
  }
  cout << res * fac[n - 1] % mod << endl;
  return 0;
}
