#include <bits/stdc++.h>
using namespace std;
long long modpow(long long x, long long y,
                 long long m = (long long)(1000000007)) {
  long long res = 1;
  while (y) {
    if (y % 2) {
      res *= x;
      res %= m;
    }
    x = x * x % (long long)(1000000007);
    y /= 2;
  }
  return res;
}
long long mypow(long long x, long long y) {
  long long res = 1;
  while (y) {
    if (y % 2) {
      res *= x;
    }
    x = x * x;
    y /= 2;
  }
  return res;
}
bool prime(long long x) {
  for (long long i = 2; i * i <= x; i++) {
    if (!(x % i)) {
      return false;
    }
  }
  return true;
}
double kyori(pair<long long, long long> f, pair<long long, long long> s) {
  double ans = 0;
  double t = fabs(f.first - s.first);
  double y = fabs(f.second - s.second);
  ans = sqrt(t * t + y * y);
  return ans;
}
long long gcd(long long x, long long y) {
  if (!y) {
    return x;
  }
  return gcd(y, x % y);
}
class Union_Find {
  vector<long long> par;
  vector<long long> rankmy;

 public:
  Union_Find(long long size) {
    par = vector<long long>(size);
    rankmy = vector<long long>(size);
    for (long long i = 0; i < size; i++) {
      par[i] = i;
    }
  }
  long long find(long long x) {
    if (par[x] == x) {
      return x;
    }
    return par[x] = find(par[x]);
  }
  void unite(long long x, long long y) {
    x = find(x);
    y = find(y);
    if (x == y) {
      return;
    }
    if (rankmy[x] < rankmy[y]) {
      par[x] = y;
    } else {
      par[y] = x;
      if (rankmy[x] == rankmy[y]) {
        rankmy[x]++;
      }
    }
  }
  bool same(long long x, long long y) { return find(x) == find(y); }
};
template <class T>
class SegTree {
  long long n;
  vector<T> data;
  T def;
  function<T(T, T)> operation;
  function<T(T, T)> update;
  T _query(long long a, long long b, long long k, long long l, long long r) {
    if (r <= a || b <= l) return def;
    if (a <= l && r <= b)
      return data[k];
    else {
      T c1 = _query(a, b, 2 * k + 1, l, (l + r) / 2);
      T c2 = _query(a, b, 2 * k + 2, (l + r) / 2, r);
      return operation(c1, c2);
    }
  }

 public:
  SegTree(size_t _n, T _def, function<T(T, T)> _operation,
          function<T(T, T)> _update)
      : def(_def), operation(_operation), update(_update) {
    n = 1;
    while (n < _n) {
      n *= 2;
    }
    data = vector<T>(2 * n - 1, def);
  }
  void change(long long i, T x) {
    i += n - 1;
    data[i] = update(data[i], x);
    while (i > 0) {
      i = (i - 1) / 2;
      data[i] = operation(data[i * 2 + 1], data[i * 2 + 2]);
    }
  }
  T query(long long a, long long b) { return _query(a, b, 0, 0, n); }
  T operator[](long long i) { return data[i + n - 1]; }
};
vector<long long> v[100004];
bool went[100004];
void dfs(long long x) {
  went[x] = true;
  for (long long i = 0; i < (long long)v[x].size(); i++) {
    if (!went[v[x][i]]) {
      dfs(v[x][i]);
    }
  }
}
long long keta(long long x) {
  long long ans = 0;
  while (x) {
    x /= 10;
    ans++;
  }
  return ans;
}
long long ketasum(long long x) {
  long long ans = 0;
  while (x) {
    ans += x % 10;
    x /= 10;
  }
  return ans;
}
long long lcm(long long x, long long y) {
  long long ans = x / gcd(x, y) * y;
  return ans;
}
long long twobeki(long long x) {
  long long ans = 0;
  while (1) {
    if (!(x & 1)) {
      ans++;
      x /= 2;
    } else {
      break;
    }
  }
  return ans;
}
long long fukugen(vector<long long> l) {
  long long ans = 0;
  for (long long i = 0; i < l.size(); i++) {
    ans *= 10;
    ans += l[i];
  }
  return ans;
}
long long n, ans, x[100004], ki[100004];
signed main() {
  cin >> n;
  ki[1] = 1;
  for (long long i = 2; i <= n; i++) {
    ki[i] = ki[i - 1] * i;
    ki[i] %= (long long)(1000000007);
  }
  for (long long i = 0; i < n; i++) {
    cin >> x[i];
  }
  for (long long i = 0; i < n; i++) {
    long long kari = ki[n - 1];
    kari *= modpow(i + 1, (long long)(1000000007) - 2);
    kari %= (long long)(1000000007);
    kari *= i;
    kari %= (long long)(1000000007);
    ans += (ki[n - 1] - kari) * (x[n - 1] - x[i]);
    ans %= (long long)(1000000007);
  }
  cout << ans << endl;
}
