// Original C++ solution (slower):
#include<bits/stdc++.h>

#include<iostream>

#include<cstdio>

#include<vector>

#include<string>

#include<algorithm>

#include<map>

using namespace std;

#define rep(i,x) for(ll i = 0; i < (ll)(x); i++)

#define pb push_back

#define eb emplace_back

#define debug(x) cerr << #x << ": " << (x) << "\n";

#define all(x) (x).begin(), (x).end()

typedef long long ll;

typedef long double ld;

typedef pair<int,int> P;

typedef pair<ll,ll> Pll;

typedef vector<ll> vl;

typedef vector<vector<ll>> vvl;

typedef vector<vector<vector<ll>>> vvvl;

const ll INF = numeric_limits<ll>::max()/4;

const ll MOD = 1e9+7;

const int n_max = 1e5+10;



void print() {

    cout << endl;

}



template <class Head, class... Tail>

void print(Head&& head, Tail&&... tail) {

    cout << head;

    if (sizeof...(tail) != 0) cout << ' ';

    print(forward<Tail>(tail)...);

}



template <class T>

void print(vector<T> &vec) {

    for (auto& a : vec) {

        cout << a;

        if (&a != &vec.back()) cout << ' ';

    }

    cout << endl;

}



template <class T>

void print(vector<vector<T>> &df) {

    for (auto& vec : df) {

        print(vec);

    }

}



const ll MAX = 1e5+10;

long long fac[MAX], finv[MAX], inv[MAX];



// テーブルを作る前処理

void COMinit() {

    fac[0] = fac[1] = 1;

    finv[0] = finv[1] = 1;

    inv[1] = 1;

    for (int i = 2; i < MAX; i++){

        fac[i] = fac[i - 1] * i % MOD;

        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;

        finv[i] = finv[i - 1] * inv[i] % MOD;

    }

}



// 二項係数計算

long long COM(int n, int k){

    if (n < k) return 0;

    if (n < 0 || k < 0) return 0;

    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;

}



ll modinv(ll a, ll m){

    ll b = m, u = 1, v = 0;

    while(b){

        ll t = a/b;

        a -= t * b; swap(a,b);

        u -= t * v; swap(u,v);

    }

    u %= m;

    if(u < 0) u += m;

    return u;



}



int main(){

    ll n; cin >> n;

    vector<ll> x(n);

    rep(i,n) cin >> x[i];

    ll ans = 0;

    // assert(n <= 2000);

    vector<ll> dp(n+10,0);

    dp[0] = 1;

    rep(i,n)dp[i+1] = dp[i] * (i+1) % MOD;

    // print(dp);

    // rep(i,n-1){

    //     ll dis = x[i+1]- x[i];

    //     ll temp = dp[n-1];

    //     temp = (temp * dp[n-1] / (n-i-1));

    //     ans += temp * dis;

    //     ans %= MOD;

    // }

    COMinit();

    // rep(i,n)rep(j,n){

    //     if(i >= j)continue;

    //     ll dis = x[j] - x[i];

    //     ll temp;

    //     if(j == n-1){

    //         temp = dp[n-1] * modinv((j-i), MOD);

    //     }

    //     else{

    //         temp = (COM(n-1, j-i+1) * dp[j-i-1]) % MOD;

    //         temp = (temp * dp[n-j+i-2]) % MOD;

    //     }

    //     temp %= MOD;

    //     // debug(i);debug(j);

    //     // debug(temp);

    //     ans = (ans + (temp * dis) % MOD) % MOD;

    // }

    vector<ll> dp2(n+10);

    dp2[0] = 0;

    rep(i,n+1){

        dp2[i+1] = (dp2[i] * (i+1)) % MOD + (dp[i+1] * modinv((i+1), MOD)) % MOD;

        dp2[i+1] %= MOD;

    }

    // print(dp2);

    rep(i,n-1){

        ll dis = x[i+1]- x[i];

        ll temp = dp2[i+1];

        temp *= (dp[n-1] * modinv(dp[i+1], MOD)) % MOD;

        temp %= MOD;

        ans = (ans + (temp * dis) % MOD) % MOD;

    }

    cout << ans << endl;

}

// Optimized solution to the same problem (faster):
#ifdef LOCAL

#define _GLIBCXX_DEBUG

#endif

#include<bits/stdc++.h>

using namespace std;

#define rep(i,s,t) for(ll i = (ll)(s); i < (ll)(t); i++)

#define rrep(i,s,t) for(ll i = (ll)(s-1);(ll)(t) <= i; i--)

#define all(x) (x).begin(), (x).end()

typedef long long ll;

typedef long double ld;

typedef pair<ll,ll> Pll;

typedef vector<ll> vl;

typedef vector<vl> vvl;

typedef vector<vvl> vvvl;

constexpr ll INF = numeric_limits<ll>::max()/4;

constexpr ll n_max = 2e5+10;

#define int ll



template <typename A, typename B>

string to_string(pair<A, B> p);

string to_string(const string &s) {return '"' + s + '"';}

string to_string(const char *c) {return to_string((string) c);}

string to_string(bool b) {return (b ? "true" : "false");}

template <size_t N>

string to_string(bitset<N> v){

    string res = "";

    for(size_t i = 0; i < N; i++) res += static_cast<char>('0' + v[i]);

    return res;

}

template <typename A>

string to_string(A v) {

    bool first = true;

    string res = "{";

    for(const auto &x : v) {

        if(!first) res += ", ";

        first = false;

        res += to_string(x);

    }

    res += "}";

    return res;

}

template <typename A, typename B>

string to_string(pair<A, B> p){return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";}



void debug_out() {cerr << endl;}

template<typename Head, typename... Tail>

void debug_out(Head H, Tail... T) {

    cerr << " " << to_string(H);

    debug_out(T...);

}



#ifdef LOCAL

#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)

#else

#define debug(...) 42

#endif



template<class T>

bool chmax(T &a, T b){if(a < b){a = b; return true;} return false;}

template<class T>

bool chmin(T &a, T b){if(a > b){a = b; return true;} return false;}



template<std::int_fast64_t Modulus>

class modint {

    using i64 = int_fast64_t;



    public:

    i64 a;



    constexpr modint(const i64 x = 0) noexcept {

        this -> a = x % Modulus;

        if(a < 0){

            a += Modulus;

        }

    }

    constexpr int getmod() { return Modulus; }

    constexpr modint operator - () const noexcept {

        return a ? Modulus - a : 0;

    }

    constexpr const i64 &value() const noexcept {return a;}

    constexpr modint operator+(const modint rhs) const noexcept {

        return modint(*this) += rhs;

    }

    constexpr modint operator-(const modint rhs) const noexcept {

        return modint(*this) -= rhs;

    }

    constexpr modint operator*(const modint rhs) const noexcept {

        return modint(*this) *= rhs;

    }

    constexpr modint operator/(const modint rhs) const noexcept {

        return modint(*this) /= rhs;

    }

    constexpr modint &operator+=(const modint rhs) noexcept {

        a += rhs.a;

        if(a >= Modulus) {

            a -= Modulus;

        }

        return *this;

    }

    constexpr modint &operator-=(const modint rhs) noexcept {

        if(a < rhs.a) {

            a += Modulus;

        }

        a -= rhs.a;

        return *this;

    }

    constexpr modint &operator*=(const modint rhs) noexcept {

        a = a * rhs.a % Modulus;

        return *this;

    }

    constexpr modint &operator/=(modint rhs) noexcept {

        i64 a_ = rhs.a, b = Modulus, u = 1, v = 0;

        while(b){

            i64 t = a_/b;

            a_ -= t * b; swap(a_,b);

            u -= t * v; swap(u,v);

        }

        a = a * u % Modulus;

        if(a < 0) a += Modulus;

        return *this;

    }

    

    // 自前実装

    constexpr bool operator==(const modint rhs) noexcept {

        return a == rhs.a;

    }

    constexpr bool operator!=(const modint rhs) noexcept {

        return a != rhs.a;

    }

    constexpr bool operator>(const modint rhs) noexcept {

        return a > rhs.a;

    }

    constexpr bool operator>=(const modint rhs) noexcept {

        return a >= rhs.a;

    }

    constexpr bool operator<(const modint rhs) noexcept {

        return a < rhs.a;

    }

    constexpr bool operator<=(const modint rhs) noexcept {

        return a <= rhs.a;

    }

    constexpr modint& operator++() noexcept {

        return (*this) += modint(1);

    }

    // constexpr modint operator++(int) {

    //     modint tmp(*this);

    //     operator++();

    //     return tmp;

    // }

    constexpr modint& operator--() noexcept {

        return (*this) -= modint(1);

    }

    // constexpr modint operator--(int) {

    //     modint tmp(*this);

    //     operator--();

    //     return tmp;

    // }

    template<typename T>

    friend constexpr modint modpow(const modint &mt, T n) noexcept {

        if(n < 0){

            modint t = (modint(1) / mt);

            return modpow(t, -n);

        }

        modint res = 1, tmp = mt;

        while(n){

            if(n & 1)res *= tmp;

            tmp *= tmp;

            n /= 2;

        }

        return res;

    }



    friend constexpr string to_string(const modint &mt) noexcept {

        return to_string(mt.a);

    }

};



// 標準入出力対応

template<std::int_fast64_t Modulus>

std::ostream &operator<<(std::ostream &out, const modint<Modulus> &m) {

    out << m.a;

    return out;

}

template<std::int_fast64_t Modulus>

std::istream &operator>>(std::istream &in, modint<Modulus> &m) {

    ll a;

    in >> a;

    m = modint<Modulus>(a);

    return in;

}



const ll MOD = 1e9+7;

// const ll MOD = 998244353;

using mint = modint<MOD>;



signed main(){

    cin.tie(nullptr);

    ios::sync_with_stdio(false);

    ll n; cin >> n;

    vector<mint> x(n);

    rep(i,0,n)cin >> x[i];

    mint fact = 1;

    vector<mint> dp(n-1);

    dp[0] = 1;

    rep(j,1,n-1){

        dp[j] = dp[j-1] * j;

        dp[j] += dp[j-1] + fact;

        fact *= (j + 1);

    }

    debug(dp);



    mint ans = 0;

    mint tfact = 1;

    rep(i,0,n-1){

        ans += (x[i+1] - x[i]) * dp[i] * fact / tfact;

        tfact *= (i + 2);

    }



    cout << ans << "\n";

}

// Fastest known solution for this problem: