#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <typeinfo>
#include <numeric>
#include <functional>
#include <unordered_map>
#include <bitset>
#include <stack>


using namespace std;
using ll = long long;
using ull = unsigned long long;

const ll INF = 1e16;
const ll MOD = 1e9 + 7;

#define REP(i, n) for(ll i = 0; i < n; i++)




















template<int MOD_>
class ModInt {
private:
public:
	long long val;
	constexpr ModInt(long long v = 0) noexcept : val(v % MOD_) {
		if (val < 0) val += MOD_;
	}
	constexpr int getmod() { return MOD_; }
	constexpr ModInt operator - () const noexcept {
		return val ? MOD_ - val : 0;
	}
	constexpr ModInt operator + (const ModInt& r) const noexcept { return ModInt(*this) += r; }
	constexpr ModInt operator - (const ModInt& r) const noexcept { return ModInt(*this) -= r; }
	constexpr ModInt operator * (const ModInt& r) const noexcept { return ModInt(*this) *= r; }
	constexpr ModInt operator / (const ModInt& r) const noexcept { return ModInt(*this) /= r; }
	constexpr ModInt operator % (const ModInt& r) const noexcept { return ModInt(*this) %= r; }
	constexpr ModInt operator ^ (const ModInt& r) const noexcept { return ModInt(*this) ^= r; }
	constexpr ModInt operator & (const ModInt& r) const noexcept { return ModInt(*this) &= r; }
	constexpr ModInt operator | (const ModInt& r) const noexcept { return ModInt(*this) |= r; }
	constexpr ModInt& operator += (const ModInt& r) noexcept {
		val += r.val;
		if (val >= MOD_) val -= MOD_;
		return *this;
	}
	constexpr ModInt& operator -= (const ModInt& r) noexcept {
		val -= r.val;
		if (val < 0) val += MOD_;
		return *this;
	}
	constexpr ModInt& operator *= (const ModInt& r) noexcept {
		val = val * r.val % MOD_;
		return *this;
	}
	constexpr ModInt& operator /= (const ModInt& r) noexcept {
		long long a = r.val, b = MOD_, u = 1, v = 0;
		while (b) {
			long long t = a / b;
			a -= t * b; swap(a, b);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD_;
		if (val < 0) val += MOD_;
		return *this;
	}
	constexpr ModInt& operator %= (const ModInt& r) noexcept {
		assert(r != 0);
		val = val % r.val;
		return *this;
	}
	constexpr ModInt& operator ^= (const ModInt& r) noexcept {
		val = (val ^ r.val) % MOD_;
		return *this;
	}
	constexpr ModInt& operator &= (const ModInt& r) noexcept {
		val = val & r.val;
		return *this;
	}
	constexpr ModInt& operator |= (const ModInt& r) noexcept {
		val = (val | r.val) % MOD_;
		return *this;
	}
	constexpr bool operator == (const ModInt& r) const noexcept {
		return this->val == r.val;
	}
	constexpr bool operator != (const ModInt& r) const noexcept {
		return this->val != r.val;
	}
	constexpr bool operator < (const ModInt& r) const noexcept {
		return this->val < r.val;
	}
	constexpr bool operator > (const ModInt& r) const noexcept {
		return this->val > r.val;
	}
	constexpr bool operator <= (const ModInt& r) const noexcept {
		return this->val <= r.val;
	}
	constexpr bool operator >= (const ModInt& r) const noexcept {
		return this->val >= r.val;
	}
	constexpr bool operator && (const ModInt& r) const noexcept {
		return this->val && r.val;
	}
	constexpr bool operator || (const ModInt& r) const noexcept {
		return this->val || r.val;
	}
	constexpr ModInt& operator ++ () noexcept {
		val = (val + 1) % MOD_;
		return *this;
	}
	constexpr ModInt operator ++ (int n) noexcept {
		ModInt<MOD_> t = *this;
		val = (val + 1) % MOD_;
		return t;
	}
	constexpr ModInt& operator -- () noexcept {
		val = (val - 1 + MOD_) % MOD_;
		return *this;
	}
	constexpr ModInt operator -- (int n) noexcept {
		ModInt<MOD_> t = *this;
		val = (val - 1 + MOD_) % MOD_;
		return t;
	}
	constexpr ModInt operator ! () noexcept {
		return val ? 1 : 0;
	}
	friend constexpr ostream& operator << (ostream &os, const ModInt<MOD_>& x) noexcept {
		return os << x.val;
	}
	friend constexpr istream& operator >> (istream &is, ModInt<MOD_>& x) noexcept {
		return is >> x.val;
	}
	friend constexpr ModInt<MOD_> modpow(const ModInt<MOD_> &a, long long n) noexcept {
		if (n == 0) return 1;
		auto t = modpow(a, n / 2);
		t = t * t;
		if (n & 1) t = t * a;
		return t;
	}
};




int main() {
	ll n;
	cin >> n;
	vector<ll> x(n);
	REP(i, n) {
		cin >> x[i];
	}
	ModInt<MOD> ans, t = 0, r = 1;
	REP(i, n - 1) {
		t += ModInt<MOD>(1) / ModInt<MOD>(i + 1);
		ans += t * (x[i + 1] - x[i]);
        r *= (i + 1);
	}
	cout << ans * r << endl;
}

Measured memory_bytes: 1024