#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;


template<std::uint_fast64_t Modulus>
class modint {
    using u64 = uint_fast64_t;

    public:
    u64 a;

    constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
    constexpr u64 &value() const noexcept {return a;}
    // constexpr const u64 &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 {
        u64 exp = Modulus - 2;
        while(exp) {
            if(exp & 1) {
                *this *= rhs;
            }
            rhs *= rhs;
            exp /= 2;
        }
        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;
    }

};

using mint = modint<MOD>;
// かなり怪しい、標準入出力対応
template<class modint, class T>
std::ostream &operator<<(std::ostream &out, const modint &mint) {
    out << mint.a;
    return out;
}
template<class modint>
std::istream &operator>>(std::istream &in, modint &mint) {
    in >> mint.a;
    mint.a %= MOD;
    return in;
}


int main(){
    ll n; cin >> n;
    vector<mint> x(n);
    rep(i,n)cin >> x[i];
    mint k = 1;
    rep(i,n-1)k *= (i+1);
    vector<mint> dp(n-1), sum(n,0);
    rep(i,n-1)dp[i] = (k / (i+1));
    rep(i,n-1)sum[i+1] = sum[i] + dp[i];
    mint ans = 0;
    rep(i,n-1){
        mint dis = x[i+1] - x[i];
        mint temp = sum[i+1] - sum[0];
        ans += temp * dis;
    }
    cout << ans.a << endl;
}

Measured memory_bytes: 2560