#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

using namespace std;

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using ll=long long;
using R=long double;
const R EPS=1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R& r){return(r > EPS)-(r < -EPS);}
inline R sq(R x){return sqrt(max(x,0.0L));}

template<typename T> vector<T> make_vector(size_t sz){
	return vector<T>(sz);
}

template<typename T,typename... Ts> 
auto make_vector(size_t sz, Ts... ts){
	return vector<decltype(make_vector<T>(ts...))>(sz, make_vector<T>(ts...));
}

template<typename T,typename U,typename... V> 
typename enable_if<is_same<T, U>::value!=0>::type 
fill_value(U &u, const V... v){
	u=U(v...);
}

template<typename T,typename U,typename... V>
typename enable_if<is_same<T, U>::value==0>::type
fill_value(U &u, const V... v){
	for(auto &e:u){
		fill_value<T>(e,v...);
	}
}

const int dx[8]={1,0,-1,0,1,-1,-1,1};
const int dy[8]={0,1,0,-1,1,1,-1,-1};

const pid_t pid = getpid();
// Problem Specific Parameter:

class ModInt {
public:
	static unsigned MOD;
	ModInt(): x(0) {}
	ModInt(signed y) : x(y >= 0 ? y % MOD : MOD - (-y) % MOD) {}
	ModInt(signed long long y) : x(y >= 0 ? y % MOD : MOD - (-y) % MOD) {}


	// Arithmetic Oprators
	ModInt &operator+=(ModInt that) {
		if ((x += that.x) >= MOD) x -= MOD; 
		return *this;
	}
	ModInt &operator-=(ModInt that) {
		if ((x += MOD - that.x) >= MOD) x -= MOD; 
		return *this;
	}
	ModInt &operator*=(ModInt that) {
		x = 1LL * x * that.x % MOD;
		return *this;
	}
	ModInt &operator/=(ModInt that) {
		return *this *= ModInt(get<1>(extgcd(that.x, int(MOD))));
	}
	ModInt &operator%=(ModInt that) {
		x %= that.x;
		return *this;
	}

	ModInt &operator+=(const int that) { return *this += ModInt(that);}
	ModInt &operator-=(const int that) { return *this -= ModInt(that);}
	ModInt &operator*=(const int that) { return *this *= ModInt(that);}
	ModInt &operator/=(const int that) { return *this /= ModInt(that);}
	ModInt &operator%=(const int that) { return *this %= ModInt(that);}

	// Comparators
	bool operator <(ModInt that) { return x < that.x; }
	bool operator >(ModInt that) { return x > that.x; }
	bool operator<=(ModInt that) { return x <= that.x; }
	bool operator>=(ModInt that) { return x >= that.x; }
	bool operator!=(ModInt that) { return x != that.x; }
	bool operator==(ModInt that) { return x == that.x; }

	// Utilities
	unsigned getval() const { return x;}
	ModInt operator+(ModInt that) const { return ModInt(*this) += that;}
	ModInt operator-(ModInt that) const { return ModInt(*this) -= that;}
	ModInt operator*(ModInt that) const { return ModInt(*this) *= that;}
	ModInt operator/(ModInt that) const { return ModInt(*this) /= that;}
	ModInt operator%(ModInt that) const { return ModInt(*this) %= that;}
	ModInt operator+(const int that) const { return ModInt(*this) += that;}
	ModInt operator-(const int that) const { return ModInt(*this) -= that;}
	ModInt operator*(const int that) const { return ModInt(*this) *= that;}
	ModInt operator/(const int that) const { return ModInt(*this) /= that;}
	ModInt operator%(const int that) const { return ModInt(*this) %= that;}
	ModInt operator=(const int that) { return *this = ModInt(that);}
	friend istream &operator>>(istream& is, ModInt &that) {ll tmp; is >> tmp; that = ModInt(tmp);return is;}
	friend ostream &operator<<(ostream& os, const ModInt &that) { return os << that.x; }
	
	ModInt power(ll n) const {
		ll b = 1LL, a = x;
		while(n){
			if(n & 1) b = b * a % MOD;
			a = a * a % MOD;
			n >>= 1;
		}
		return ModInt(b);
	}
private:
	unsigned x;
	
	inline tuple<int, int, int> extgcd(int a, int b) {
		if (b == 0) return make_tuple(a, 1, 0);
		tuple<int, int, int> ret = extgcd(b, a % b);
		swap(get<1>(ret), get<2>(ret));
		get<2>(ret) -= a / b * get<1>(ret);
		return ret;
	}
};

unsigned ModInt::MOD = 1000000007;
using mint = ModInt;
const mint ZERO = mint(0);
const mint ONE = mint(1);
const mint TWO = mint(2);

vector<mint> Fact, InvFact;
void makeFact(int n){
	Fact = vector<mint>(n+1);
	Fact[0] = mint(1);
	rep(i,1,n+1) Fact[i] = mint(i) * Fact[i-1];
}

mint Factorial(int n){ return Fact[n];}

int main(void){
	int n;
	cin >> n;
	vector<int> x(n);
	rep(i, n) cin >> x[i];

	makeFact(n);
	const mint base_coef = Factorial(n - 1);
	mint coef = ZERO;

	mint ans = ZERO;

	rep(i, 1, n){
		const int d = x[i] - x[i - 1];
		coef += base_coef / mint(i);
		ans += coef * mint(d);
	}

	cout << ans << endl;

	return 0;
}

Measured memory_bytes: 1024