#include <bits/stdc++.h>

using namespace std;
#define rep(i, N) for(int i=0;i<int(N);++i)
#define rep1(i, N) for(int i=1;i<int(N);++i)
#define all(a) (a).begin(),(a).end()
#define print(v) { cerr<<#v<<": [ "; for(auto _ : v) cerr<<_<<", "; cerr<<"]"<<endl; }
#define printpair(v) { cerr<<#v<<": [ "; for(auto _ : v) cerr<<"{"<<_.first<<","<<_.second<<"}"<<", "; cerr<<"]"<<endl; }
#define dump(x) cerr<<#x<<": "<<x<<endl;
#define bit(k) (1LL<<(k))
typedef long long ll;
typedef pair<int, int> i_i;
typedef pair<ll, ll> l_l;
template<class T> using vec = vector<T>;
template<class T> using vvec = vector<vec<T>>;

template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
    os << "{" << p.first << ", " << p.second << "}";
    return os;
}

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

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

const int INF = (ll) 1e9;
const ll INFLL = (ll) 1e18 + 1;
const ll MOD = (ll) 1e9 + 7;
const double PI = acos(-1.0);

/*
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 string dir = "DRUL";
*/
struct mint {
    long long x;

    mint(long long _x = 0) : x((_x % MOD + MOD) % MOD) {}

    mint operator-() const { return mint(-x); }

    mint &operator+=(const mint a) {
        if ((x += a.x) >= MOD) x -= MOD;
        return *this;
    }

    mint &operator-=(const mint a) {
        if ((x += MOD - a.x) >= MOD) x -= MOD;
        return *this;
    }

    mint &operator*=(const mint a) {
        (x *= a.x) %= MOD;
        return *this;
    }

    mint operator+(const mint a) const {
        mint res(*this);
        return res += a;
    }

    mint operator-(const mint a) const {
        mint res(*this);
        return res -= a;
    }

    mint operator*(const mint a) const {
        mint res(*this);
        return res *= a;
    }

    mint modpow(long long t) const {
        if (!t) return 1;
        mint a = modpow(t >> 1);
        a *= a;
        if (t & 1) a *= *this;
        return a;
    }

    // for prime MOD
    mint inv() const {
        return modpow(MOD - 2);
    }

    mint &operator/=(const mint a) {
        return (*this) *= a.inv();
    }

    mint operator/(const mint a) const {
        mint res(*this);
        return res /= a;
    }

    friend std::ostream &operator<<(std::ostream &os, const mint &a) {
        os << a.x;
        return os;
    }
};

struct combination {
    vector<mint> fact, ifact;

    //constructor(initiation)
    combination(int n) : fact(n + 1), ifact(n + 1) {
        assert(n < MOD);
        fact[0] = 1;
        for (int i = 1; i <= n; ++i) fact[i] = fact[i - 1] * i;
        ifact[n] = fact[n].inv();
        for (int i = n; i >= 1; --i) ifact[i - 1] = ifact[i] * i;
    }

    mint Comb(int n, int k) {
        if (k < 0 || k > n) return 0;
        return fact[n] * ifact[k] * ifact[n - k];
    }

    mint H(int n, int m) {
        return Comb(n + m - 1, m);
    }
} C(200100);

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    int N;
    cin >> N;
    vector<ll> x(N);
    vector<ll> d(N - 1);
    for (int i = 0; i < N; ++i) {
        cin >> x[i];
        if (i > 0)d[i - 1] = x[i] - x[i - 1];
    }
    mint ans = 0;
    mint tmp = 0;
    rep(i, N - 1) {
        tmp += mint(i + 1).inv();
        ans += C.fact[N - 1] * mint(d[i]) * tmp;
    }
    cout << ans << endl;
}

Measured memory_bytes: 4992